- Edited
3DCenter.org has compiled a list of relative performance of the GeForce RTX 2080 Ti against the GeForce GTX 1080 Ti. This list matches the games tested and Numbers by the Turkish Tech Channel at Youtube (Video dropped) and Joker and The Good Old Gamer talked about on Youtube.

An average increase of 37.5 % looks good in rasterization rendering - No DLSS and RT , with some games tipping to 50 % + increase. Sure they are still leaks and done on immature drivers , but overall Turing looks promising.
Read more: https://www.tweaktown.com/news/63041/geforce-rtx-2080-ti-37-5-faster-overall-gtx-1080/index.html

An average increase of 37.5 % looks good in rasterization rendering - No DLSS and RT , with some games tipping to 50 % + increase. Sure they are still leaks and done on immature drivers , but overall Turing looks promising.
Read more: https://www.tweaktown.com/news/63041/geforce-rtx-2080-ti-37-5-faster-overall-gtx-1080/index.html