Hi. You should have your employer write a letter that they will give you a promotion after your course is done and that they will give you a leave for you to go and continue your studies first. Hence showing you still have a job back home to go back to.
Use family and properties owned by you or your parents as ties to go back to. You may need to revamp your SOP for this.
Based on your explanation, I am assuming you have a study gap as you have been working. Clearly explain the gap in your studies and why you are choosing CANADA as a place to study now.