Can I get a job with an airline after I qualify as a Commercial Pilot?

No, you require additional qualifications with your Commercial Pilot Licence.  Generally speaking, an “airline” is a commercial air carrier that operates with seating capacity for 19 passengers or more.  Since aircraft that carry this capacity have two or more engine, you will be required to hold a Multi-engine Class Rating.  Also, because airlines operate their aircraft in the full range of weather conditions, you will require a Group 1 (Multi-engine) Instrument Rating, which qualifies you to fly visual conditions of flight when you cannot see the ground or horizon—for example, making a landing at Vancouver Airport when there are low clouds.  After you acquire these ratings, you effectively meet Transport Canada’s personnel requirements for airline pilots, but you still require an Individual Type Rating for the aircraft you will be flying—usually, the airline you fly with will look after the training required for this, but in Canada you must complete Transport Canada Examinations in order qualify for such a rating.

So flying for the airlines will entail more than just your Commercial Pilot Licence, but the good news is that the cost of these additional training is normally a lot less than the accumulated costs of obtaining your Commercial Pilot Licence (which includes time building as well as the Private Pilot Licence).

Most commercial pilot students complete their Multi-engine Class Rating and their Group 1 (Multi-engine) Rating concurrently so they are absolutely focused on just multi-engine operations by the time they do the flight tests required for these two ratings.  Ideally they start their Instrument Ratings in a multi-engine simulator to complete the bulk of their Instrument Rating training, and they brake off to completed the training and flight test for the Multi-engine Rating—the simulator gets them comfortable with working two throttles, two propeller control levers, and two mixtures, etc.  Then they stay in the airplane—when they are at their best—to complete the final hours of instrument training leading up to their flight tests.

Commercial Pilots students can write the qualifying examination for the Individual Type Rating-Aeroplane (IATRA) with as little as 125 hours flying experience and with Class 1 (Commercial Pilot) medical certificate.  This exam is valid for two years and, when they complete their Commercial Pilot Licence, and their Group 1 (Multi-engine) Instrument Rating, makes them ready for that first job as a co-pilot (Second-in-Command) in the airlines!

Courtesy Wikipedia, Langley Flying School.