2 1080ti's. That is a lot of GPU power to throw at any CPU. If u ask about bottleneck, the answer is no at 4k resolution. However, if u game on 1440p or 1080p, u will face some bottleneck.
A friend of mine has 6700k with 2 1080ti's. He faces mild bottleneck playing some games at 1080p. At, 4k, this will not happen. And, if u have a good enough cooler, OC that 7700k to as high as u can to reduce any chance of bottleneck.
I can suggest u to go for 6800k (6 cores/12 Threads). But, in most games, 7700k will beat the 6800k because of it's higher single core frequency.
SO, stick with the 7700k and buy a very good cooler. Corsair H100i V2 is a nice choice. Or, Noctua NHD15 if u prefer Air cooling. Although, i suggest water cooling at...