Most definitely.
It’s seen better days and current expansion is kinda meh, but it’s still leading the amount of active players by a lot over all other MMO games.
It’s really hard to know for sure, because Blizzard don’t release statistics, but according to ActivePlayer.io, Final Fantasy XIV has more active players than World of Warcraft.
But there are other websites which put World of Warcraft in the lead. It’s also worth mentioning that World of Warcraft has much higher twitch statistics than FFXIV.
Hm last I checked it said WoW had a lot more, I think mostly due to the new expansion at the time. But I think different sources are stating different things, they’re pretty unclear where they get the numbers from anyway, there’s little consistency with other statistics online.
It’s hard to get exact numbers from WoW because they’re not publicly available. You might be right that WoW is still the biggest, I found some other numbers that disagree. WoW’s twitch numbers seem to be way higher.
I’ll edit my comment