I could send you several studies on that topic. In fact, both participation rates and program completion rates vary according to people's socio-economic level. That is true for aboriginals. I have the impression that there are also nuances based on access. However, the results are not as clear as far as the variation in tuition fees is concerned. That does not appear to have a major impact on access, even among lower-income people.
On June 13th, 2006. See this statement in context.