How can a human like Yuto or Abe no Seimei live in Magano? In the 16 and 17th episode, we can see that Yuto probably lives in Magano since he appeared out of nowhere and left by jumping around, presumably to his hideout, instead of using Magano Gate directly.
Also, in episode 18, we can see Yuto placing flowers on the Hinatsuki Dorm in Magano, waiting for Rokuro to arrive. This means he is somehow, at least, camping there.
Also, according to the wiki,

Abe no Seimei is still alive in Magano

Is it possible for humans to 'camp' in Magano? Do humans who pass through the Magano gate not need nourishment?
The fact, that Abe no Seimei is still alive in Magano, was just barely mentioned in manga, and there was no real proof for that.

Nevertheless, in ch. 17 of manga, it was shown, that exorcist may survive really long time without any supplies, based only on his divine powers. So, I suppose, the strongest exorcist in history may stay alive in Magano for really long time.

Regarding Yuto, question is slightly incorrect, since according to ch. 13,


   Yuto is no longer human anymore, he is much more like Basara being - he infected himself with Impurity, and managed to gain control over it.