A 777 could glide for about 20 minutes without 2 engines but factor weather conditions, weight from the fuel which takes some to dump, passenger load and cargo plus the time of day it would be very unlikely you would be able to land a 777 on water without it ripping a part. Here;s what would most likely happen if a water landing was attempted on a large plane like the 777;
And the miracle on the Hudson was just that, a miracle.