The “red ending” of Mass Effect 3, for those who haven’t experienced it, has Shepard gasp for air right before the credits rolls. While that is somewhat ambiguous as to his final fate, BioWare’s Tully Ackland confirmed that it means that Shepard does live in that ending.
“You may notice that in the ‘Shepard lives’ ending, the love interest hesitates to place Shepard’s name on the wall, and instead looks up as though deep in thought,” wrote Ackland. “This is meant to suggest that the love interest is not ready to believe Shepard is dead, and the final scene reveals they are correct. As the Normandy lifts off, there is hope that the love interest and Shepard will again be together.”
Source: BioWare.com
