Fellow Ghostbusters veteran Dan Aykroyd confirmed Murray's return on The Greg Hill Show. While it always seemed likely Murray would return to his iconic role for the new film, this is the first time we've gotten actual confirmation. In addition to Murray and Aykroyd, original Ghostbusters stars Ernie Hudson, Sigourney Weaver and Annie Potts have also been confirmed to return.
I haven't been keeping up with this but apparently a few cast members have been confirmed.
Ghostbusters 3 director Jason Reitman has confirmed Carrie Coon (Gone Girl, The Leftover's) along with McKenna Grace (Captain Marvel, (upcoming) Annabelle Comes Home) and Finn Wolfhard (Stranger Things, It) will star in the long-awaited sequel.