I found this on ellisisland.org – Passenger Louis de Lioncourt boarding the ship La Bretagne in the port of Havre on March 5, 1907. His place of origin shows as Bordeaux. Top photo shows a page of La Bretagne’s manifest – next is a photo of the La Bretagne, then a closer shot of the manifest, line 22. The last picture gives the information shown on the manifest.
Looks like Louis sailed to New York (perhaps with Armand ?) in 1907 and used Lestat’s name as a pseudonym.
what a find! mon dieu!