There are many families with that surname that came either from the "Pale of Settlement" or from Tsarist Imperial Russia mostly as peasant Jews. The root is Gonchar (see NOTE), which in most slavic languages means "Potter", thus when adding the Russian suffix "owski" or any variant, it changes it to mean "Of/from the ... Estate". The common variants I've seen are as follows: German: Ganz, Gans, (Gonczarowski, Gonszarowski - Germanized Polish variants); Polish: Gonsiorowski, Gonsior, Gąsiorowski; Russian: Гончаровский, Гончар; Hebrew/Yiddish: גאנשעראװסקי . My own family changed theirs to Ganz/Gans when they came to NY from Kowal/Wloclawek, Poland.
NOTE - It has come to my attention that there are two variant meanings to the name. The Polish root forms mean "Gander", which is a male goose. These forms come from the Germanic form of the word for goose, Gans/Ganz. The non-Polish root forms derive from the Slavic translation of the root, "Potter".