Sponsoring parents can easily take 4-5 years but there is no problem sponsoring someone who is already on a work permit. You could also sponsor his spouse and dependent children but you need to show that you have income to support them.
When you say he is already sponsored by his spouse but on a work permit, you mean that he has a work permit because his spouse has one or you mean that his spouse is sponsoring him inland and he has received 1st stage approval? If it is the latter, he will likely have PR from his inland application long before your sponsorship of him even starts to get processed.
