I think this guy is looking at AIB partner cards only and assuming those will be the best full fat 80 CU SKU's, this is what Igore did. Turns out AMD are keeping the full fat 80 CU SKU for themselves..
I can imagine a cut down 72 CU 6900XT at 2.1Ghz AIB card being a match for the 3080 with AMD's exclusive 80 CU at 2.2Ghz (6900XTX?) pushing it a little past the 3080.
10% more CU's than a 3080 equivalent is probably very close to a 3090...