As far as fans are aware, the Halo Infinite release date is still down for holiday 2021 - which Microsoft reconfirmed at E3 2021 in June - but otherwise, we still don't have a firm date. That may have changed this week, as a partnership between Xbox and Krispy Kreme may have inadvertently leaked the Halo Infinite release month.
The story spoilers and the possibility of multiple campaigns being leaked thanks to that technical preview - but this particular leak comes via the unusual combination of Halo, Krispy Kreme, and Xbox.
Leading up to the release of Halo Infinite, Krispy Kreme has announced that it will be selling a special Halo doughnut as of July 30 - which is basically a normal chocolate-covered doughnut with Master Chief's face on it. The interesting part, however, is that the official Xbox Mexico sent a tweet out about the new doughnut with the words "why wait for November if we can start the festivities now?"
The tweet going on to note that the collaboration is also to celebrate the 20th anniversary of the Halo series and Master Chief - as the original Halo: Combat Evolved Halo Infinite is still definitely launching Autumn or Holiday 2021 then November would make a lot of sense.
https://twitter.com/XboxMexico/status/1420172732331921410
By all s, with multiple story expansions too. As for whether we'll see all this in November, we'll have to wait and see.