Pâté Chinois is not a Chinese recipe. It may simply be an adaption of "Shepherd's Pie", but one possible explanation for the Chinese reference is that it was introduced to Canadian railway workers by Chinese cooks during the building of the North American railroads in the late 19th century. These cooks made it under instruction from the railway bosses (of English extraction) as an easily prepared, inexpensive version of the popular cottage pie, with the sauce in the tinned creamed corn serving as a substitute for the gravy.
The French Canadian railway workers became fond of it and brought the recipe back with them to their home communities. From there, it was brought to the textile mill communities of Maine (Lewiston and Biddeford), New Hampshire (Manchester, also home to Nicholas Paquet), Massachusetts (e.g., Lowell and Lawrence) and Rhode Island (Woonsocket) where many French Canadians immigrated to work in the mills during the early 20th century. It may also be connected to the town of China, Maine. Some Lewiston, Maine families made a variation called Pâté au Chinois layering the dish with mashed potatoes at the bottom, ground beef next, followed by peas, whole beets, and creamed corn on the top.