I think there's a chance that he was with the 84th Highland Regiment which was offered land in Nova Scotia after the American Revolution. There's a book I've heard of but not seen that is reported to contain a list of the soldiers who settled there, "Rawdon and Douglas: Two Loyalists Townships in Nova Scotia." I have his daugher, Mary married to the son of another man I believe was with the regiment by the name of George White. If what I have about George White is correct (not certain) he was pressed into service in New York after the colonies revolted in 1776. Suppose that might be the same or similar fate of William Gill.