The first player would win. In omaha you must always use exactly 2 of your hole cards and 3 of the board cards to make your best possible 5 card hand.
The best hand player one can make is using his 2 Kings and 3 of the queens on the board for queens full of kings (QQQKK)
The best hand the other player can make is using his 2 sixes and 3 of the queens on the board for queens full of sixes (QQQ66).