I'm not sure what the deal is with the brown garment (possibly it's a drape), but underneath it the man is wearing a white cassock surplice and a falling collar, a style which replaced the ruff through the early 17th century. Judging by the shape of the collar and the style of his hair and facial hair, I would suspect that this portrait is likely from the 1640s.

It might help for identification if you can tell us where you found the painting, what the context is around it, etc.