The Nintendo Shop on the Switch lists the game's "Number Of Players" as "1 or more". On the computer I navigated to Nintendo.com and it says "to be determined".
Is the game multiplayer or not?
From what I know Octopath Traveler is single player only.
There are no multiplayer options on the title screen. While I'm still working my way though the first chapter of each character's story, I haven't seen anything in-game to indicate there is multiplayer either.