No, it’s not dead. The number of players is irrelevant.

A “dead game” is a game that needs work but is not under any development. It could be in Early Access, and incomplete. Or, it could be released, but still incomplete (looking at you, 7 Days to Die). Or, it could be an MMO that needs ongoing server maintenance, but they shut the servers down.

A game that is being worked on and making good progress isn’t dead. A game that is complete and relatively bug-free, but not being worked on, is not dead. An MMO getting no new content, but just enough labor to keep the lights on and the servers up, is not dead.

I guess an MMO or multiplayer game that has mandatory multiplayer aspects could be considered Dead if there aren’t enough players available to reasonably play the game. But Palworld is a single player game, or co-op with friends, not really an MMO.