Shortly before Battle of Crait we see Resistance soldiers occupying trenches and gun emplacements ahead of the large armored base door.
Later those positions were attacked by Tie fighters, but the Millennium Falcon draws them away. It doesn't look like they were destroyed, especially since Poe, after his failed run on battering ram cannon, manages to run to them and finds them still occupied. Also, after breaching the base door, the First Order opens fire on Luke, but not on those positions.
What happened to those soldiers ?
It is highly unlikely they were evacuated in small Millennium Falcon, the only Resistance craft still operational after the battle.