Have you had any luck? I too am looking for information on the "Gaillard's" from New York.
My Great-Grand-Aunt Helene Birkenruth married a man with the last name "Gaillard". They lived in or near "Astoria, Queens, New York". They also may have live at one time near the Bronx.
For more info: Helene was born in Stipshausen, Germany and migrated to the USA on September 11th, 1912. Unfortunatley I don't know the first name of the man she married, just know his last name was "Gaillard"