Toby, that depends on if they believe you. It is possible that they scan the passport and/or PR card without stamping anything and then they would have a record but even if they don't, they may find that he has been living in Canada just by checking official information, where he lives, works etc.
Employment records: Yes, if he works some place, that is proof of time in Canada.
Passports as proof of time in Canada: I doubt that CIC checks passport scans, or else surely they would not ask renewing PRs to fill out those tedious forms, and would not ask PRs for receipts and a host of other proofs. If this assumption is true, then passport stamps are a poor proof (ditto boarding passes), because they only tell CIC that the PR was outside Canada on the dates testified by those particular exit/entry stamps. As someone said recently in this forum, one can travel to the US without any stamps in one's passport. So, CIC cannot conclude from the absence of other stamps that all "non-stamped" time was spent in Canada; the PR might have been in the USA for part of this time too. And so, CIC cannot use the passport as a primary proof of time in Canada.
The problem is when they don't believe which is why PRs should save boarding cards, plane and bus tickets and various other souvenirs for just in case anybody will ever ask.
Again, such receipts show time out of Canada. It is not necessarily true that all other time was spent in Canada.
Saving receipts can be a good idea too, for example gas station receipts or ATM receipts.
Yes, this type of receipt shows time IN Canada, so save them. Time spent in Jail is also germaine, as long as the sceptical CIC officer doesn't wonder if you secretly escaped from prison, lived in another country for a few years, then tunnelled back int prison to appear to have lived in Canada all the time. /color]
