You won't see any difference from the i5 to the i7. In simplistic terms, the i7 is just the i5 with hyperthreading which doesn't benefit games much at all, or not at all. You'll be golden with the 4570.
Are you building a new PC? We could possibly give you a recommendation if you give us a budget.
u wont be able to see the difference, in todays games, smarter to get a 4670k and overclock it, that will outperform a 3770 or 3770k with hyperthreading, ht isnt even supported in most games, they gotta be coded to include ht. and arent in 99% of games of today.
so yeah u wont see a difference between both if ur using identical gpus and memory and are at stock speeds.