We were promised a multiplayer beta for halo infinite but we have no information on it. Halo 5’s beta released nearly a year before the final game and we are less than a year away from infinite. I think 343 just decided to give up the idea of a beta but I still have hope it will release soon.
There will be a beta, or what 343 is now calling “flights” my understanding is that there are plans for multiple. no word on a date yet. Be sure to sign up, here is the link:
343 is still planning on having flights for Halo Infinite.
They said there will be testing/flights. Best bet is to wait between late spring to summer for more news and dates.
I think with 343 changing the engine that Infinite is built on multiple times and with the working from home that 2020 brought it really slowed down the progress but I am sure there will be a “beta” or “flights” soon. With the limited information available currently I suspect the multiplayer may be slightly behind on progress compared to the campaign but that is purely speculation.