It's such a cliche of course after the first game in a seven game series but if Pit loses this game they have a very big hill to climb.
Whowins.com has the odds for these sorts of things and shows that 70 times in the NHL a visiting team has won the first two games and 76% of the time they go on to win the series.
Finer resolution shows it's happened 24 times in the 1st round and 67% of the time they win the series.
As for winning the first game on the road in a first round series? 71 teams have one the first on the road and 36 have gone on to win the series for a 51% winning percentage.
I'm thinking this game goes big either way - either Elliot or Fleury implode. I'll be overly optimistic and say 5-1 Sens.