Yes, he is eligible to get his taxes back if he is still your dependent on your tax return. He is not required to file at all if his W-2 is less than $6300... so if he files, he would get his taxes withheld back.
If he is self-employed, it is a little different story... He must file if he made more than $400 as self-employed and tax refund will depend on his net self-employed income.
