All living creatures born of the flesh shall sit at last in the boat of the West, andwhen it sinks, when the boat of Magilum sinks, they are gone; but we shall go forward and fixour eyes on this monster
This quote is showing how Gilgamesh is telling Enkidu how he will not have peace if Enkidu leaves this battle first. Gilgamesh was trying to make Enkidu feel bad because he is reminding him of how when this boat full of people, peoples lives, will die and it will be his fault. But, if he commits to that, he will still have to go on and fight.