According to Jerry Bails' Who's Who (
http://bailsprojects.com/whoswho.aspx) Gill was a staff artist for the New York daily News from 1940-1946. Prior to that he had done some work for Centaur, MLJ, Fox and Fiction House in 1938-1940.
Besides his newspaper art duties other work in the first half of the 1940s listed for Gill on Who's Who consists of:
Catechetical Guild-
Topix-1944
Chesler-various features-1942
DC-
Picture Stories From the Bible-c.1942-1945
Dell-
Those Remarkable Heroes-1943,
War Heroes-1943-1944
Novelty-
Blue Bolt-1944-1946, various features and covers-1944-1946
Parents Magazine Press-
True Comics-1943-1947
He seems to have left the Daily News when he sold his
Flower Potts/Ricky Stevens comic strip in 1946. After the strip folded in 1949 he was doing comic books regularly into the 1970s as well as teaching art (1948-1990) at various institutions.
Best
Joe