Maybe if he does give you a gift you will luck out and it would be appropriate - a box of candy (not Godiva chocolates though), a candle, a glass apple, some ballons, a teacher-ish book or flowers (though red roses might be different). Something like that, which you could display on your desk for everyone to enjoy, would probably be OK. If this happens to be the case I'd say just accept the gift then display them for everyone to look at/share and write him a thank you note but of course keep it professional - don't sign your first name or anything too "friendly."
If he does give you an inappropriate gift, such as something overly romantic or whatever, I'd just thank him but tell him in private that while you appreciate his thoughts you can't accept this gift as his teacher.
He's not 7, or even 13, he sounds old enough to know better.