Survivor is a game where participants predict the winner or loser (depending on pool format) of one game per picking period.
Unless the poolie is making their pick from a Thursday game - our football Survivor has a hard cutoff of the first game of the week that is played AFTER Thursday. Please see this help article for a listing of cutoffs for the 2017 NFL season. If a poolie does not make their pick in time for this cutoff, they will lose a life.
If a tie occurs, it is the same as getting your pick wrong. So if your format is WINNER - your pick must WIN to survive. If your format is LOSER - your pick must LOSE to survive.