Only the first ace would count as 11 (as with any hand that is only if it does not put the total over 21). Any additional aces would count as 1.
Although you wouldn't usually (playing American BS) have a hand consisting exclusively of 3+ Aces (like AJL said, since you'd normally split them), you could have a multi-Ace soft hand from hitting a soft hand and getting more Aces (though there would typically be at least one non-Ace card in the hand).