Borderline stuff can last a few hours. I've occasionally seen linkjacked stuff that is several hours old. The story being jacked is interesting, and so it may even have upvotes. Obviously, once a moderator spots it, the link gets changed to the original story...but it'd be hard to spot in a quick peruse of the New page, so I can understand how such links could live so long.

Anyway, it depends on your definition of "survived" and whether there is value for the spammer in their story living on the new page for minutes or hours. Our company forums get an onslaught of spam about once per week, and though the spam never lasts more than a few hours (far less these days, as I've added a couple of moderators), it seems to be the same spammer doing it over and over again, so they must consider it worth a shot. When your employees time is almost free (or the work is done by a bot), pretty much any result is a worthwhile result.