The funny thing about Apex Legends is that its being promoted as "a small studio built this despite EA" yet a mass-media marketing campaign was saturating the internet even before the game launched and yet the game was just announced.
Meaning, no one knew about it, yet the moment it was announced there were articles on it everywhere on hundreds if not thousands of sites.
In other words, despite the narrative being pushed, you can tell EA threw their marketing weight behind this and the media, likely some paid for their rah-rah efforts, were all too happy to take the money and perpetuate the (not-so-)organic popularity of the game thereby self-fulfilling the hype.
I'm not saying its not a good or great game, but I saw articles on the game on several sites I visit including some where it was "stuck" to the top (aka: above the fold) section of a site for a prolonged amount of time even before most people had heard of the game.
I think it is more likely if the game is as good as the hype makes it out to be, it will ultimately acquire more PUBG players than non-PUBG Fortnite players (meaning people who play Fortnite that never played PUBG).
Add to that the game has no Nintendo Switch or mobile support and it will be hard-pressed to surpass Fortnite beyond the initial mass-marketing launch phase.
The surge of a FREE game is not surprising no matter the numbers downloading and playing it. The real test is when games like Fortnite manage to hold on to those players months later.