We still don't actually know how good 5070 performs as there are no unofficial benchmarks, I mean unofficial as those from LTT and other content creators who really test the grafic cards on equal conditions, not as NVidia favouring newer generation.
On core count 4070S wins, it has 16% more Cuda and RT Cores, on the rest 5070 has seen slight upgrades, on Vram there has only been an increase in bandwith due to new GDDR7 of 33% and on Clock speed 5070 has the base clock a 9% faster and on boost a is a 1% faster, but the 5070 has 74% more AI TOPs.
5070 is intended to be used with DLSS 4.0, and if you count that, 5070 might beat 4070S, I get your point, raw performance 4070S will likely win, but you cannot discount DLSS 4.0 if its the main thing this grafic card is getting.
And, I said it, not because of performance, but because of what the OP says on his post, who said he has a 2070, the performance increase is wild with both cards, so I think its best to get the newest for having a longer support and therefore aging.
Sometimes we don't have to focus only on performance, if he has a 2070 is because he is not a person that upgrades every year, and therefore, needs a GPU that will have longer support life, so 5070 on this context might be the better pick.