How much more fps through i7 / i9?

I have a - rtx 2070 Super, a Ryzen 5 2600x 3.6 ghz, 16gb DDR4 3000 mhz RAM, a 500gb SSD, 1 TB HDD and it all sits on the B450M pro vdh plus.

With this system I reach between 180-240 fps, in fps shooters like Overwatch.

How much more fps would I get with an i7 / i9?

I saw a streamer on Twitch that had an rtx 2070, an i9 9900k 16gb ddr4 3200 mhz Ram and constantly reached 250-300 fps in this game…

Does the processor matter so much?

To say badly depends on the details of the respective game. Can be 55 can also be more than 70, more or less.

The 9700k oc does it with the left

If you play with low graphics settings, the CPU is of course more important than your graphics card.

In this area, Intel is also significantly better and therefore you will get at least 1/3 higher frame rates with an i9 9900K.