You are eligible to sponsor your wife while living outside Canada. You can sponsor her outland if you wish to remain in US while awaiting PR sponsorship. If the wife has been living in US for more than 1 year, she can request that the papers be sent to US instead of pakistan. If wife has a Canadian visa, you and your wife can move to Canada and start inland sponsorship. But that involve quitting your job in US and finding another job before starting your sponsorship.
It depends on what you wants to do. Inland if possible or outland. To answer your question, as a Canadian you can sponsor your wife for PR.