Asked about the raw gaming performance in current games, Nvidia's Director of Technical Marketing Tom Petersen stated that the new RTX 2000 GPUs are between 355 and 45% faster than the Pascal cards. However, upcoming games may perform better if they are specifically coded to take advantage of the new Turing Tensor cores that facilitate the DLSS tech.
https://www.notebookcheck.net/Nvidia-official-says-the-RTX-20xx-cards-are-at-best-45-faster-than-the-Pascal-counterparts.328192.0.html