Seriously tho is he ded or what?
The Distortion World seems like it is breathable, and there is water. If Lucas/Dawn caught Giratina, then he has no threats. However, the only thing that seems edible in there are those dead looking plants, and I doubt that's going to help much. He could eat his Pokemon, but that's not going to last him forever, and since they're all males, he can't breed them so he has a sustainable food source. So he has probably died by now, unless I am seriously underestimating the nutritional value of Distortion World trees.
He transcended into a higher being in the Distortion World. Literally became a god. He altered the world to become the world he wanted. He created
Kyurem eats humans but I think Giratina is just a misunderstood Big Friendly, it probably didn't do anything to him after it dragged him in.
Cyrus will be back...eventually. Whenever Game Freak happens to remember and they think it's the right time.
Cyrus and giratina met and mated, they are the first pokemon/human couple. They have decided not to leave the Distortion World due to societal problems (and arceus). They have three beautiful children and Cyrus has been able to make a small shack to house them in, giratina feeds the babies regularly since she's the mother.