Max Gebhardt is listed in the "Death Books from Auschwitz" with prisoner number 22488 and the date of death 19 August 1942. This means that rather than having been sent to the gas chambers from the ramps of Auschwitz, he was instead recruited for forced labor. His deportation date may have been days or even months prior to his date of death. The date listed above as his date of death in September 1942 is probably the date of death used in a postwar death declaration.
Source: State Museum of Auschwitz-Birkenau: "Death Books from Auschwitz", KG Saur 1995.