Head into Saint Denis and over towards the Tailor to meet up with Trelawny. Head inside and browse the catalogue to buy the outfit Trelawny had reserved and then head over to the Barbers to freshen up. Once you’re satisfied, board the wagon to make your way to the Grand Korrigan.
During the poker game, you’ll be able to look at Strauss to find out which way to bet however if you do so, you’ll void the Gold Medal. Instead, choose to Fold on the first hand and then go All-in on the subsequent hands. Eventually, you’ll clean up and need to head upstairs with the pit boss to retrieve the watch from the office. Once you go to loot the safe however, the pit boss pulls another sidearm out, quickly aim at his head and put him down.
As you make your way back downstairs, you’ll intervene in an argument at the bar when all hell breaks loose. You’ll have to play this entire sequence perfectly in order to get the Gold Medal. The exit is the door at the back, to the right of the stairs and you’ll need to reach it and jump overboard within 35 seconds. To make this even more difficult you’ll have to score at least 5 headshots so you’ll need to be on the move firing in Dead Eye while working towards the door. The first three guards in front of you should be your first targets, headshot them with Dead Eye as you walk towards the exit. Ignore the others and you’ll spot two more coming down the stairs, headshot them (with Dead Eye) and then quickly head through the door once it opens and jump off the side. Even with this, the timing is incredibly tight and will take multiple attempts (from the start of the mission, not the checkpoint) to execute perfectly.