~에 갈 것입니까? is actually not used either in spoken or written korean. in both ways, it sounds weird. ~에 갈 겁니까? is also sounds too formal, I think it's only used in army or something. try these when you talk to someone who's older than you or who's not close to you, you could say formally: ~에 갈거에요? or ~에 가실거에요? when you talk to your friends or close ones : ~에 갈거야? -> 내일 학교에 갈거야?

Those are same meaning. But '~갈 겁니까? ' is spoken language . '~갈 것입니까?' is formal &written language.