How about taking your mind off the possible Native connection, of which there is only a very slim chance with most French-Canadians, and focusing on the genealogy part? Have you posted the information you have to the GILBERT surname board and asked for help? Have you searched under the French spelling Guilbert? Have you obtained birth, marriage, and death records for everyone possible? In the USA did you obtain the Social Security applications and all military records? People are willing to help you online once you have done your homework as much as you can.
(This message and the one to which it responds have been moved to the Canada>General board because they are not specific to the locality where they were posted.)