In Scarface the time only jumps a few months at times but it is obviously longer, so how much time goes by from beginning to end.
Tony Montana was born May 5th, 1940. The Movie starts with the Mariel boat lift, the Cuban Refugee arrival in Miami, in May 1980. The Movie ends on roughly the End of November/Start of December 1983, with Tony's death. Various sources give a few different dates surrounding that week. Wikipedia has it listed as December 9, 1983 (coincidently the same day as the movie's release date.)
So start to finish is roughly 3 years 8 months.