according to this site:
http://www.ancestry.com/search/SurnamePage.aspx?html=b&ln=Pabis&sourcecode=13304 it's a Polish pet form of Pabian, which is a variant of
Fabian, which is derived from
Fabius, meaning 'bean' (
http://www.behindthename.com/php/view.php?name=fabius)
And, there's already been a discussion about
Fabian and Fabis, so maybe it's interesting to read:
http://www.behindthename.com/bb/arcview.php?id=45664&board=gen