First thing first: Kudos on including a background!
That being said, there are perspective related issues that I want to point out. I'm using the bed as the reference but the most noticeable one is the tabletop with the lamp doesn't align with the bed. Is this on purpose?
One of his hand and foot lays independent of the perspective so I would re-orient them. Please excuse the clumsy looking hands, I'm unfamiliar with gorilla digits.
Speaking of feet and digits notice his other foot without the perspective issue. On the original his fingers are all parallel to each other. Seeing 5 lines in a row ||||| visually flattens the form. I would vary it a bit by angling.
His tent is a nice touch but due to its size, I would stretch out the whole front of the material.
his upper torso I've outlined how I would draw the musculature. His (stage) right hand is doing a very hard pose so I would put more attention into pinning this angle down. Perspective-wise, his bicep should be in front of this forearm.