Sega seems to think so at least, and that's good enough for us.
Leaks are getting harder and harder to avoid in the video game industry, with plenty of insiders, age-rating organisations, retailers and more spilling the beans before things have been officially announced. And to make things worse, it's also quite common that the publishers themselves leak things beforehand.
Like Sega, to take a really fresh example. They just published a Sonic Frontiers trailer on their Japanese YouTube account, which included a release date. As this obviously was meant to be shared during this evening's Gamescom Opening Night Live (starting at 19:00 BST / 20:00 CEST), it was quickly removed - but internet never misses these things and picture proof was saved by several people, including Nibel on Twitter.
Because of this, we now know fairly certainly (the source is Sega, after all) that Sonic Frontiers will be released on November 8.