My college son is in an Austism program that costs an extra $5000 a semester. Is this deductible?

Yes. The cost may be deducted as medical expenses,  on Schedule A  (itemized deductions), subject to the 7.5% of AGI threshold.  

 Alternatively, special needs cost, at college,  are qualified educational expenses for either  a tuition credit or deduction.

Being enrolled in an Autism program does not confirm to the reader of your post that your son is autistic. Anybody can be enrolled in and take such a class. But I assume your son has autism. If not, then I assume he is pursuing a course of study in autism. Is your son actually enrolled in college and taking courses that will lead to a degree or other credentialed certification? Is this special program he's enrolled in offered by the same college? If so, then I would expect it to be included in box 1 of the 1098-T which means you can claim it as part of the qualified education expenses.

Otherwise, it would be a medical expense *IF* prescribed by a licensed medical professional and subject to the 7.5% of AGI rules to be deductible as such.