It would definitely benefit you to upgrade your CPU since you're running a 144hz display and probably want to try and maintain something as close to that as possible, depending on some other factors like settings and what kind of games you tend to play of course. I have a 2060 Super, and a 144hz 1440p display as well, and I can tell you that even with my 6700k I'm looking to upgrade when the right CPU or deal comes along because I'm CPU limited right now and it's painfully obvious in some games.
I'm doubtful that a 4790k upgrade is the right one for you though, considering my 6700k is holding me back. I'd think a full platform upgrade would make a lot more sense BUT of course it's probably about 40% more expensive than just a CPU upgrade as well. Still, used Haswell i7's aren't cheap and it's money better put towards something newer that performs better AND is going to have a lot more life in it than something that's already five years old.