In the original universe, we've seen Finn's father, Martin in the episode "Escape from the Citadel". He then escaped to space, but he might have a chance of being still alive. If you're looking for Farmworld Universe, Finn's father (Mr. Mertens) ran away with his family after Ice Finn told them to do so. Not sure if he's still alive. Then after Jake's wish (In "Jake the Dog"), that universe was probably somehow altered. So who knows?
he could have entered the empty vacuum of 宇宙 and died of lack of oxygen (as he 発言しました at the end of the episode really fast as the entered the portal "hey what about oxygen?")
または he could have simply gone somewhere else 安全, 安全です as can be...
point being is we can't be sure until he resurfaces, dead または alive.
Yes as we saw in "Escape the Citadel" he went off into space. But in "The Tower" we thought Finn's father was in the tower but it was just PB in disguise. So I'm not very sure if Martin is alive または not only time will tell.