Yes and no.
If your games are cpu limited and largely single threaded, then the higher stock clock rate of a i7-4790K will help.
Games such as sims, mmo, and strategy games are usually single thread limited.
If you are using a Z97 motherboard that permits overclocking, then a i5-4690K with a decent overclock will be better.
There is little value from the I7 hyperthreads; few games can use more than 2-3 threads.
How to tell?
Here is one way:
a) Run YOUR games, but lower your resolution and eye candy.
If your FPS increases, it indicates that your cpu is strong enough to drive a better graphics configuration.
If your FPS stays the same, you are likely more cpu limited.
b) Limit your cpu, either by reducing the OC, or, in windows power management, limit the maximum cpu% to something like 70%.
Go to control panel/power options/change plan settings/change advanced power settings/processor power management/maximum processor state/
This will simulate what a lack of cpu power will do.
Conversely what a 30% improvement in core speed might do.