IELTS requirement for Canada student visa:
IELTS is compulsory component in almost all universities of Canada and you need to score about 6.5 over all which is acceptable for all Canadian universities, only in few cases or in specific courses you need different IELTS score. You must take IELTS or any other English Language Proficiency Test if you want to get admission in Canadian Universities.
Somehow it could be exempted if you proved that you have been studying or already studied in English at Higher school level for at least two years or more.
For your more information, all Canadian universities accept IELTS Academic Module for admission, for further information on Canadian universities you can visit officeial website.