I think gambling revenue - not sure if it's shared by the "partners" or just the deluge of advertising and sponsorships they're getting from gambling sites - has been a windfall. Also helmet ads, jersey ads, those dynamic board ads, etc.
Fanatics has spent a lot of money to build their merch monopoly. I'd imagine the NHL has a better licensing deal with them than the previous deals with Reebok or whoever it was.
The Rogers/Sportsnet deal was back loaded I believe. I imagine the US deal works the same way - more money each year. There's streaming and digital and whatever else they're able to squeeze money out of.
We've also added a couple of teams over the last few years that seem to be doing quite well financially and moved the black hole Phoenix/Arizona franchise out of their 5000 seat arena to Utah, which can't hurt either.
Some combination of the above, plus price increases across the board for tickets, concessions, etc...