jewishgen.org gives his date of birth as 25.10.1900 and says he married Terci Lustig in 1927. The Breslau synagogue address (ca 1930) lists his brother Norbert and sister Emma, and lists a Gustav Guttmann born 24.10.1899 married to Therese Lustig living at Kopischstrasse 82; I assume this is the same Gustav.

Gustav and Therese lived at Kurasserstrasse 153 when their German nationality was annulled.