When it comes to Fortnite, there's no p2w aspect in the Battle Royale. It's just not possible because it's luck on what you get when you jump into each game. However in terms for the PvE version of the game, yes. Impressively so is it p2w, it's even worse than most mobile games. The real way to level is through getting your gear leveled which does require you to play the game but the rewards are excessively minimal. Yet the only way to level your weapons, traps, heroes, defenders and survivors is by retiring others. And if you buy say 100 llamas you're going to be able to dump a lot of trash you get and boost your gear accordingly. But again since you won't get things like materials from llamas you still need to play the game.

I'm most definitely certain paying more will reward you greatly, as you can't expect to get the best things in life free.