I think it's clear that Fuji is better than Irie. He can use Radiant Gale to keep up with TnK which is Irie's biggest threat. Irie maybe has World of Ice, but outside of Atobe vs Ryoma, World of Ice isn't absolute.
However Scaling Fuji vs Ryoma is tricky IMO. Ryoma intentionally made the match a game of "can I return all 6 counters?" Which makes it dubious if he played seriously. We saw Ryoma return every counter, but Fuji still won the point each time. Plus he can defeat all of Ryoma's techniques.
However again, we don't see Ryoma use Samurai and the finicky wind put Fuji at advantage and disadvantage in the match. Plus Ryoma relies a lot on Special Moves which makes him the ultimate prey for Fuji's counters. So overall, I think it's hard to get a clear picture on where either stands because the match is such a mess writing wise.
I definitely do not think Fuji being better than Irie is a sure thing.
Not to mention I do believe Irie matches up well against Fuji.
He is a skilled, fast and has high mental strength.
His weaknesses are his power and stamina, not things Fuji can particularly exploit. I don't think he is truly a low stamina player either considering he played so many points with Atobe.
Irie can probably deal with most of Fuji's counters relatively easily to be honest.
None of Fuji's counters are powerful from what I remember so he can't exploit Irie's low power.
I think Irie will have the advantage until Fuji comes up with a new counter or two mid battle and then anything goes. Maybe a new counter that will be hard for Irie to return since he is "weak". Wouldn't surprise me if even his low power and stamina stats were a facade.
Let's be honest can any player play over 100 tiebreaks with 2 stamina? Seems bogus which makes me suspect Irie's stats is bs.