Unfalsifiability

I remember Bram covering the Gambler's fallacy once: "A real gambler will lose ten times and think, 'I'll bet again, I'm due for a win!', then win ten times and think 'I'll bet again, I'm on a streak!'" This is vaguely reminiscent of a statistic from Sam Harris, "a poll conducted by The Washington Post found that 80% of Katrina's survivors claim that the event has only strengthened their faith in God." I'm curious how many of these survivors are part of the 87% of Americans "who claim to never doubt the existence of God"?