Do kids with autism benefit from occupational therapy and how?

Yes. It helps to desensitize children with autism to normal world stimulation such as the feeling of clothing, or sounds or smells or sensations in the mouth.
OT is helpful. 1) fine motor skills – hand coordination/manipulation. May include skills required for education, eg. Writing. 2) self-help/adaptive skills – functions for daily living, eg. Dressing. 3) sensory reactivity – kids with autism often have sensory sensitivities (eg. May over-react to sounds not bothersome to others). 4) feeding difficulties – as related to sensory aversion or dexterity (eg. Spoon use).