Habrá beta tres días antes del lanzamiento oficial para los jugadores que reserven su copia en gamestop o a través del online (para Estados Unidos, en España no sabemos):

The “early access” experience for PowerUp Rewards members who preorder at GameStop will be available from Friday, March 15 at 11:59 p.m. PT to Monday, March 18 at 11:59 p.m. PT. This offer also applies retroactively to members who have previously preordered the game at GameStop.
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As an added bonus, multiplayer experience points (XP) earned will carry over to the final game for players who purchase and play “Judgment” in the first week following its U.S. release, allowing them to get a jump on the competition and begin unlocking special rewards, like new weapon skins, medals and achievements.
Visto en la web oficial de epicgames.

Vídeo Gears of War: Judgment OverRun Tutorial