How long must I live with a person in order to have the same rights as a legally marred person.

These are what I found looking it up
You have to live together for one straight year and assets and liabilities and that you live together in a physical dwelling. Other evidence required are joint bank statements, joint ownership of a home (or joint leases), joint utilities and joint management of household expenses, among other things.

Canada makes a distinction between a common law partner and a conjugal partner.
You have to check with your providence because they vary.