PCGamesHardware posted some new RT benchmarks covering recent hardware releases. Benchmarked at 4K max settings.
Cyberpunk 2077:
6950XT: 100%
3090Ti: 178%
4080: 225%
4090: 322%
The 4080 is 25% faster than 3090Ti and 40% faster than 3090 and 2.25x times faster than 6950XT.
Doom Eternal:
6950XT: 100%
3090Ti: 166%
4080: 200%
4090: 275%
The 4080 is 20% faster than 3090Ti and 30% faster than 3090 and 2x times faster than 6950XT.
Dying Light 2:
6950XT: 100%
3090Ti: 186%
4080: 235%
4090: 340%
The 4080 is 25% faster than 3090Ti and 40% faster than 3090 and 2.35x times faster than 6950XT.
Guardians of the Galaxy:
6950XT: 100%
3090Ti: 168%
4080: 190%
4090: 245%
The 4080 is 13% faster than 3090Ti and 22% faster than 3090 and 90% faster than 6950XT.
Lego:
6950XT: 100%
3090Ti: 164%
4080: 220%
4090: 310%
The 4080 is 35% faster than 3090Ti and 45% faster than 3090 and 2.2x times faster than 6950XT.
Metro Exodus:
6950XT: 100%
3090Ti: 155%
4080: 180%
4090: 250%
The 4080 is 15% faster than 3090Ti and 25% faster than 3090 and 80% faster than 6950XT.
Riftbreaker:
6950XT: 100%
3090Ti: 158%
4080: 196%
4090: 250%
The 4080 is 25% faster than 3090Ti and 35% faster than 3090 and 96% faster than 6950XT.
Ghostwire Tokyo:
6950XT: 100%
3090Ti: 146%
4080: 188%
4090: 255%
The 4080 is 30% faster than 3090Ti and 40% faster than 3090 and 88% faster than 6950XT.
Nvidias Geforce RTX 4080 im Spieletest mit zahlreichen Raytracing-Benchmarks in vier Auflösungen.
www.pcgameshardware.de
All in all, the 4080 is up to 35% faster than 3090Ti in heavy RT titles, on average it's ~25% faster though than 3090Ti, and ~35% faster than 3090, while being 2X faster than 6950XT. The relevancy of this is that the 4080 will easily best the upcoming 7900XTX in heavy ray tracing, by a margin that is anywhere from 20% to 40%.
Edit: corrected summary percentages ..