The i7's have HyperThreading which gives it extra threads and generally allows for a better experience in multithreaded software. Gaming these days is actually more multithreaded then it was a few years ago, especially with the arrival of the new 8 core APU consoles(PS4, Xbox One) though the games don't use all 8 cores. So you might see a bit of an advantage with an i7 especially down the road. A few years back i would have probably not recommended an i7, as we we're still limited by developers not using those extra resources, it's slowly changing.
Though gaming still is GPU centric, so it's better to focus on that mostly and just find a good CPU to balance it out. Meaning don't buy a $400 video card and pair it was a cheap i3 or i5. Spend as much on the video card as you did on the CPU give or take.