If you are talking about the following, only 1 per group. The exception is if the highest scoring players in any groups have the same score and tiebreak, then any in that situation move through.
http://www.chess.com/tournament/29th-chesscom-thematic-tournament---alekhne-1001-1200
Does someone know how many players in a group are going to advance to the next round (first 2 or 3) in the Alekhine Tournament 1001 -1200?