If it's a decisive player in field, of course it must affect the way I gamble, as I will feel tempted to cashout in order to avoid a potential bigger loss as consequence. On the other hand, if it's a replaceable player, I don't think it should change my decision to maintain the bet, because I know the team is going to have another player of the same quality to play during his absence. It really depend on each case.

Worst case is when one of the players is kicked out from the game by the referee due to a penalty. When the team has to play with one less player in field, the tendency is that they lose or play for the tie, totally defensively. On that case, it will completely change the strategy and prediction of the gambler regards the specific match on his bets.