4080 is faster by about 15% than 3090Ti. People hated it cuz it was priced pretty high, not because it's perfomance. I mean, non Ti-version of high-end card beats down the Ti version of previous gen 'top tier'.
I'm pretty sure even 4070Ti is faster than 3090Ti - no much, probably within a margin about 5-10%.
And it's just considering a 'raw power', no rtx\dlss technlogy\hardware updates.
7900XTX is almost equal to 4080. But no fancy Nvidia stuff, rtx performance is closer to 30xx cards than current Nvidia gen.
As for VaM, there was someone who tested it vs 4080 [with 13900k cpu if i recall] and 4080 was performing better.
I also wait for an 7900 xtx bench like hell, but except this anecdotical evidence - that “sumbody tried and aint worth it..” isnt really anything. Yes in VR 7xxx suxx atm, but I use it in pancake mode - aka desktop - and the 6xxx put up a pretty good fight in prev gen. So chances are that it may do it again. Sadly I cant try cuz I have a custom loop sff desktop, and exchanging hw is as painful as possible (did it on purpose
peace