Hitler is an alternative spelling to an already somewhat uncommon family name, Hiedler. It's unknown why Adolf's father Alois chose the Hitler spelling over Hiedler. Alois was born Alois Schicklgruber. He changed his name in adulthood. His stepfather (and maybe biological father) was Johann Hiedler.

It may be that Alois' choice was unique, if there were other Hitler's in Austria I haven't found them. So when we talk of "Hitlers" we are talking about Alois and his eight children.

Alois married three times. First was to Anna Glasl-Hörer with whom he had no children.

Second was to Franziska Fanni Matzelsberger. They had two children Alois Jr and and Angela. Both Alois and Angela had children and grandchildren. Alois had two boys William and Heinz. Heinz served in the German army and died in the Soviet Union in 1942. He had no children. William joined the US Navy and after the war changed his name to Stuart-Houston. William had four sons all of whom kept the Stuart-Houston name. None of them have any children, so ending Alois Jr's line.

Angela married Leo Raubal, and had three children Leo, Geli, and Elfriede, and two grandchildren Peter and Heiner. Neither Peter nor Heiner had children and at 85 and 72 neither seem likely to. None of Angela's descendants of course had the Hitler name, they were either Raubals or Hocheggars.

Alois' third marriage was to Klara Pölzl which produced Gustav, Ida, Otto, Adolf, Edmund, and Paula. Of these only Adolf and Paula survived into adulthood. Neither Adolf nor Paula ever had children. Paula also adopted the pseudonym Wolff in the 1930s and never again went by Hitler.

So Adolf's surviving family members are the six grandchildren of his half-brother and half-sister. Of those six, five were still alive in 1997. I'm not sure how many are alive today. In any case none of them carry the Hitler name. The Hitler name died with Adolf, as none of his surviving family members used it after the war.