https://render.otoy.com/octanebench/
I ran the benchmark on my RTX 2070 and it came in at 213.53, which is over twice as fast as my old GTX 980 at 97.
Results here for single GPU:
https://render.otoy.com/octanebench/results.php
Just looking at some of the results that are coming in, my RTX 2070 is just 4 points behind the GTX 1080ti. So it looks like the 2070 would be a better buy than a 1080ti, especially when the RT cores are fully supported, at least for Octane.