He is not required to file a return as long as it was W-2 income and assuming he has no other income (self-employment, investment, etc). However, he can file a return to get a refund of any taxes that were withheld (on the W-2, Box 2).
He may be able to file for free at https://turbotax.intuit.com/. If you are going to claim him on your own tax return, please make sure he indicates that he is claimed as a dependent on someone else's return when he follows the TurboTax Online interview screens.
