Is it yours? Chinchilla and grey flemmies look a lot alike! The ear length and shape along with the face slope makes me think its a flemmie though. Can you get a pic of it laying not sprawled? That'll show if its got the compact or semi arch...
Looks to be Flemish. Serena came from a shelter--she was very skinny and weighed 7 pounds and we were told she was over a year old, mostly based on her size. Found out she was a Checkered Giant and she weighs 18 pounds now. She's 3 times as big as any of our other bunnies except Lilli.
How much does he weigh? And do you have an estimated age?
There are three breeds of chinchillas.
Standard Chinchilla = Max weight 7.5 lbs
American Chinchilla = Max weight 12 lbs
Giant Chinchilla = Max weight 17 lbs
Flemish do not have a max weight but others have said their varying weights.
Edit: If she could try to pose him you could tell what kind of body shape he is. If he doesn'r start rising until past his shoulders then he is a longer typed rabbit and most likely a flemmie. If he starts rising very steadily from the nape of his neck then he is most likely a chinchilla. Adult weight would determine which one of the chins he would be.
To pose put the tip of his feet right under his eyes and the tips of his back feet in line with his hips/knees.