Jason Momoa has teased the character himself a number of times and recently was spotted training at the same location as Wonder Woman Gal Gadot.
Now a report from Empire Magazine is stating that Jason Momoa is confirmed to be Aquaman.
While Warner Bros. has not officially made the announcement (expect it when Momoa begins filming), in an article in Empire Magazine, it's stated under "Confirmation" that "Jason Momoa will be getting his Speedos on as the Atlantean ass-kicker, Aquaman."
It's possible Empire may have jumped the gun, or maybe they just happen to know that Jason Momoa is indeed Aquaman.
You can see the article for yourself in the following video:
"Batman v Superman: Dawn of Justice" has a May 6, 2016 release starring Ben Affleck as Batman, Henry Cavill as Superman, Gal Gadot as Wonder Woman, Amy Adams as Lois Lane, Laurence Fishburne as Perry White, Diane Lane as Martha Kent, Jeremy Irons as Alfred, Jesse Eisenberg as Lex Luthor, Ray Fisher as Cyborg with Callan Mulvey, Holly Hunter and Tao Okamoto in new character roles for the film. Justice League is to follow directed by Zack Snyder as well.
For more news on the "Man of Steel" and related movies head on over to the Cosmic Book News Superman movie hub.