Can you use a student ID to get discount at Gamestop?

No, you can't.

Some Gamestops will give you 5% off software (but not hardware) when you show a student ID, so don't expect a discount on game systems. Depending on how much you typically buy at Gamestop, a PowerUp Rewards account with them could be worth it. There's a free membership and pro-level membership, and in either case, you receive points for every purchase that can be redeemed on their Web site. A pro membership (for 14.99 a year) additionally gives you discounts on pre-owned games and accessories, more value for your trade-ins, and a subscription to Game Informer.