Results in Groups A and B mean that Jamaica is guaranteed a spot in the quarterfinals regardless of the outcome of this game. If it loses to El Salvador, it will slip (most likely - since Mexico is expected to beat Curacao) to third in Group C, but it has enough points (four) to be one of the lucky-losers entering the knockout rounds as one of the two best third-placed teams from the group stage.
A draw would see both Jamaica and El Salvador through to the quarterfinals, with El Salvador (unless Curacao does something very surprising against Mexico) qualifying as one of the best third-placed teams. A win for Jamaica would raise the possibility of the Reggae Boyz winning Group C (Mexico would need to beat Curacao by the right number of goals to win the group) - and could see El Salvador eliminated, depending on how its tiebreakers (goal difference and goals scored) match up with Group B's third-placed team, Martinique.
So there is a little more riding on the result of this game for El Salvador than Jamaica. But the Reggae Boyz will want to show progress from what has been an encouraging start to the Gold Cup. Don't expect either team to mail this one in, but Jamaica has more margin for error than its opponent.