I couldn't find James on the 1930 census but here is Thomas from 1910 to 1930:
1910 US census – 225 Locust Avenue, Amsterdam, Montgomery County, New York
Thomas McGaffin, boarder, 26, single, born Ireland, parents born Ireland, immigrated 1903, weaver – carpet mill
1920 US census - 350 Forest Avenue, Amsterdam, Montgomery County, New York
Thomas McGaffin, head, 39, immigrated in 1886, naturalized in 1898, born Ireland, parents born Ireland, weaver – rug mill
Annie J McGaffin, wife, 41, immigrated in 1887, naturalized in 1898, born Ireland, parents born Ireland
Jennie A McGaffin, daughter, 20, immigrated in 1915, naturalized in 1898, born Ireland, parents born Ireland, forelady – spinners rug mill
Minnie McGaffin, daughter, 17, immigrated in 1912, naturalized in 1898, born Ireland, parents born Ireland, spinner – rug mill
William G McGaffin, son, 15, immigrated in 1913, naturalized in 1898, born Ireland, parents born Ireland, doffer – rug mill
James McGaffin, son, 7, born New York, parents born Ireland
1930 US census - 350 Forest Avenue, Amsterdam, Montgomery County, New York
Thomas McGaffin, head, 49, age at first marriage: 25, born Northern Ireland, parents born Northern Ireland, immigrated in 1904, naturalized, weaver – carpet mill
Anna McGaffin, wife, 49, age at first marriage: 24, born Northern Ireland, parents born Northern Ireland, immigrated in 1901, naturalized
James McGaffin, son, 17, born New York, parents born Northern Ireland, mill hand – carpet mill
Even though the immigration and naturalization dates are all over the place, this is the same Thomas.
I’ve also found a passport application for Thomas dated 1922. His date of birth is given as 14 Mar 1880 in Bleary, Ireland. He was going to visit his father, James, in Bleary.
Jacquie