Question: does chuck die in gossip girl season 5

Answer: No, At the beginning of the season Chuck and Blair make a pact not to be together until Blair succeeds at Waldorf designs and Chuck takes down Bart. After many failed attempts of taking down Bart, Bart and Chuck end up in a fight. This leads to Bart falling off a building and dying. Blair is the only witness to this event and so Chuck and Blair get married so Blair does not have to testify against Chuck.