You could catch the Skytrain from Waterfront Station on Cordova(not Canada Line to the airport) to Main Street Station and the Pacific train station is across the street. There is good signage for the station when leaving Canada Place.. The trains are frequent and the trip is short. You would have to drag your luggage a block or so on either end which may be more than you want to do. The line to get taxis can be very, very long so I think that Uber is a better bet to get to the train station.