Worn by: Mark Wahlberg as Jim Bennett
Reference: Omega Speedmaster
Brand: Omega
Mark Wahlberg (playing Jim Bennett) is wearing an Omega Speedmaster in The Gambler. He even gives the watch a mention in this movie: "It's an Omega, it's worth more than six thousand brand new". Our guess is that it is a Co-Axial 44.25mm version of the Speedmaster.
Source: https://www.fratellowatches.com/speedmaster-in-movies/