As you know, children with autism have a broad range of skills.
Some children with autism have severe communication deficits. Others struggle with social skills and pragmatics.
Unresolved reading problems have a negative impact on thinking, behavior, and self-concept.
If reading difficulties are allowed to continue, your child's problems will only get worse. Don't delay getting an evaluation.
If your child is verbal, he should have the same skills tested as a typical child. If he has difficulty decoding, this is usually due to weaknesses in phonemic awareness and/or rapid naming so these skills need to be assessed.
Consult with your evaluator about your child's oral language skills and whether he needs additional testing in this area.
Children who read poorly and/or slowly have difficulty remembering what they read. Reading can be hard and unpleasant.
See Table 6-1. Reading Tests and the Skills They Measure in Wrightslaw: All About Tests and Assessments, 2nd Edition, page 60. On page 63, you'll find Table 6-2. Tests That Measure Reading Skills in Nonverbal Children.