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But can he come to canada

Without the details of what the charge was and when the jail sentence was completed, the most we can say is that it may be possible for him to come to Canada but not until several years from now.
 
What if the person gets a job in canada? Or what if the person gets family reunifed in canada?

If they are inadmissible, then entering Canada is still going to be a problem. Having a job in Canada or family in Canada doesn't fix this.