At the end of DB, Miraak gets tentacled by Mora. And when we're absorbing his "soul" it say's, "Dragon soul absorbed" and we get a bunch of Dragonsouls, but isn't possible that we where just absorbing the souls of the dragons he's killed, not his soul, Bethesda could have easily put, "MIRAAK'S SOUL ABSORBED" Like how they put "Miraak absorbed a dragon soul" when he absorbs the souls of the dragons you slay? Think about it, at the end of the MQ Akatosh intervenes and saves Alduin from being consumed, is it possible for Akatosh that he did the same thing for his other wayward son.

Well, unless you think he somehow survived the whole "Ack, my body is disintegrating thing", whist his essence flowing directly into the Dragonborn, then yes. He's as dead as a box of dodo's.

Well his flesh burnt away like a normal dragon's when you absorb its soul and the essence definitely went into you, so I don't think his soul went to Akatosh. What would Akatosh want with it anyway? Miraak's just a regular dragon(born) anyway while Alduin is at least semi-divine, possibly another facet of Akatosh.