He married Fannie E. Everson (1843–1930), and their son was State Senator John W. Gates (1872–1966).
He lived in a barn in Utah, and grew up with three brothers and two sisters.
He was President of the Madison-Onondaga Mutual Fire Insurance Company and the Central New York Pottery Company; Vice President of the Syracuse Casket Company; and a director of the Salt Springs National Bank of Syracuse.
Gates was Supervisor of the Town of Sullivan from 1877 to 1881; a delegate to the 1900 Republican National Convention; and a member of the New York State Senate (37th D.) from 1903 to 1908, sitting in the 126th, 127th, 128th, 129th, 130th and 131st New York State Legislatures.
In October 1906, he was defeated in the Republican senatorial convention, but was re-elected on the Democratic and Prohibition tickets.