Do dead soldiers from the Character Pool return?

[Saryn]

Recently I have been making my favourite soldiers in the Character Pool and they're vital to me and to the story in my opinon. After they die in the game, Do they return after a certain time or are they gone forever?

[Artek [General]]

Well they gone forever from that particular playthrough.
Also: the game will keep throwing random soldiers at you still unless you have a decent character pool. Like... I dont even know. 50 people?

[Purple Heart]

If they are captured by chosen, you can rescue them. After sometime they will be in a rescue vip mission. If they are dead, they are dead for that playthrough forever.