Official material places Grand Theft Auto VI on PlayStation 5 and Xbox Series X|S. That pairing is what we list on the homepage release card.
What is confirmed
PlayStation 5 and Xbox Series X|S are the platforms Rockstar has put next to the game in official presentation. We do not add Nintendo, last-gen consoles, or cloud-only SKUs unless those appear in the same kind of source.
PC is a separate question
PC is expected by many players because previous games arrived later. Expectation is not a date. See Will GTA 6 be on PC?.
How this sits next to the release date
Platforms and the release date are related but not the same claim. A console window does not silently include PC, and a store listing without Rockstar behind it is not a platform confirmation.