My understanding is that more CU's with a slower clockrate usually beats less CU's with a higher clockrate even with equal flops, and XSX has a nearly 2 tflop advantage. On top of that, the PS5 is using boost clocks to arrive at their figures, so there will be times when it is outputting less power than advertised, if the system starts to get too hot. So yeah, XSX definitely has the technical advantage, except for PS5 having a faster SSD.
Now if we're talking sales, obviously Sony has the advantage due to a much strong worldwide presence and an already established quality 1st party. That being said, Xbox is a in a much better situation sales wise than they were this gen; they didn't botch the reveal (quite the opposite in fact), they have the specs crown with XSX (and will also have the cheapest next-gen console if Series S is real), and their 1st party for next-gen is looking way stronger than it was for XB1, thanks to multiple studio acquisitions and hiring sprees. I think that will be enough for MS to take back the US and possibly the UK, while also gaining some ground in mainland Europe and the rest of the world.