According to the Illinois marriage database from Illinois courthouse records which is available on line, there was a marriage of a Minnie ANN James to a Mr. James Edward Dupuy on April 24, 1897 in Piatt Co.

I would suggest requesting a copy of the marriage license to see if his age is given and that way you could possibly link him to an 1880 census household. If you do that and find his age, let me know and I can look for them if you need help.

I would also suggest contacting the Piatt Co genealogy or historical society to see if there is a burial for James Edward Dupay between 1897 and 1900 at the time of the census. He may be buried near other Dupay family members. Also check nearby counties as well if that doesn't net you anything. I did see a couple 1880 listings in the census for a James Dupuy of Schuyler Co, IL, but no way to identify either of them as your James Edward Dupay just yet. My time is extremely limited right now to do any research, but I just decided to check this out on a whim