If USA wins against Canada (has to be in regulation), they need to win big (or destroy the Czech's in the final game).
Canada is +6
Europe is +4
USA is -3
don't have to win big. In a 3 way tie ROW is the first tiebreaker, followed by regulation wins. If USA beats Canada and the Czechs in regulation then they're through with 4 points, 2 ROW, 2 regulation wins.
Either Canada would have less than 4 points(if Europe beats Canada), or Canada/USA would have a tie at 4 points for 2nd with Europe at 5 and USA advances on h2h(if Canada wins in OT or SO) or it's a 3 way tie at 4 points(Canada win in regulation) and USA and CAN advance on tiebreakers with 2 ROW and 2 regulation wins while Europe would only have 1 regulation win.
With this game going to OT, I don't believe there can be a 3 way tie on points, ROW and regulation wins anymore in this group and thus goal differential will now be irrelevant.