There are clips of Grand Theft Auto VI posted to an online forum.
The user, screen name "teapotuberhacker", uploaded 90 videos to the site and claimed they could leak more data soon.
An email and phone number for Take2 employees were provided in a Sunday update.
The statement said that he was looking to negotiate.
The game will not be ready for release for at least two years. There are parts of the game that are unfinished.
According to his sources, the leak was confirmed by the reporter.
The leaked videos are being widely shared on social media and some of them have been flagged for violating copyrighted material.