this is not for my own child but for a close family members child who is now 2yr 3months, if he had autism, what would the symptoms be?

There are three distinctive behaviors that characterize autism. Autistic children have difficulties with social interaction, problems with verbal and nonverbal communication, and repetitive behaviors or narrow, obsessive interests. These behaviors can range in impact from mild to disabling.

I know it must be hard for your friends waiting for the diagnosis, but autism is a complex disorder. A comprehensive evaluation requires a multidisciplinary team including a psychologist, neurologist, psychiatrist, speech therapist, and other professionals who diagnose children with ASDs. the team members will conduct a thorough neurological assessment and in-depth cognitive and language testing. Because hearing problems can cause behaviors that could be mistaken for autism, children with delayed speech development should also have their hearing tested. After a thorough evaluation, the team usually meets with parents to explain the results of the evaluation and present the diagnosis.

Possible Early Signs of Autism Spectrum Disorders include

Children and adults with an autism spectrum disorder might:
•Not play "pretend" games (pretend to "feed" a doll)
•Not point at objects to show interest (point at an airplane flying over)
•Not look at objects when another person points at them
•Have trouble relating to others or not have an interest in other people at all
•Avoid eye contact and want to be alone
•Have trouble understanding other people's feelings or talking about their own feelings
•Prefer not to be held or cuddled or might cuddle only when they want to
•Appear to be unaware when other people talk to them but respond to other sounds
•Be very interested in people, but not know how to talk to, play with, or relate to them
•Repeat or echo words or phrases said to them, or repeat words or phrases in place of normal language (echolalia)
•Have trouble expressing their needs using typical words or motions
•Repeat actions over and over again
•Have trouble adapting to changes in routine
•Have unusual reactions to the way things smell, taste, look, feel, or sound
•Lose skills they once had (for instance, stop saying words they were once using)
•Talk to your child’s doctor or nurse if your child loses skills at any age.

Examples of Specific Language Issues
•repeats words/phrases of others (Echolalia)
•uses own language (jargoning)
•repeats a word or phrase
•reverses pronouns I/me/my and you/your
•refers to self by name
•does not respond to conversational initiation
•gives unrelated answers to questions
•makes comments unrelated to conversation topic
•does not point
•does not respond to pointing
•uses few or no gestures
•talks in monotone or robot-like
•does not respond to own name
•no pretend play; doesn’t understand pretend play
•does not understand jokes, sarcasm, idioms, teasing, or similes

Examples of Specific ASD Repetitive Behaviors and Unusual Interests
•lines up toys
•plays with toys in same manner every time
•is very organized
•is rigid about routines or object placements
•upset by changes
•eat few foods or only certain textures
•eats inedible things (pica)
•smells food
•insensitive to pain
•unaware of danger (e.g., hot things)
•tantrums for no apparent reason
•has obsessive interests
•hand flapping/finger flicking/toe walking
•self-stimulation
•likes spinning objects
•likes to spin him/herself
•likes parts of objects (e.g., wheels)
•does not use toys appropriately (lines up cars by color rather that zooming them)
•special areas of talent or expertise
•perseveration
•walks over things (e.g., toys) unaware

Hear are some "red flags" for autism in early childhood

Communication
• no babbling by 11 months of age
• no simple gestures by 12 months (e.g., waving bye-bye)
• no single words by 16 months
• no 2-word phrases by 24 months (noun + verb – e.g., “baby sleeping”)
• no response when name is called, causing concern about hearing
• Loss of any language or social skills at any age

Behaviour
• Odd or repetitive ways of moving fingers or hands
• Oversensitive to certain textures, sounds or lights
• Lack of interest in toys, or plays with them in an unusual way (e.g., lining up, spinning, opening/closing parts rather than using the toy as a whole)
• Compulsions or rituals (has to perform activities in a special way or certain sequence; is prone to tantrums if rituals are interrupted)
• Preoccupations with unusual interests, such as light switches, doors, fans, wheels
• Unusual fears

Social
• Rarely makes eye contact when interacting with people
• Does not play peek-a-boo
• Doesn’t point to show things he/she is interested in
• Rarely smiles socially
• more interested in looking at objects than at people’s faces
• Prefers to play alone
• Doesn’t make attempts to get parent’s attention; doesn't follow/look when someone is pointing at something
• Seems to be “in his/her own world”
• Doesn’t respond to parent’s attempts to play, even if relaxed
• Avoids or ignores other children when they approach

I also have issues with my son's Autism. I posted my question on wish123 and got an answer from an expert who solved my problem. Worth a try.

You could notice that he doesn't talk until an older age than most little kids.

What makes you think he is autistic?

the only one i know of is walking on their tip toes alot…