Austin is obviously not Polish, and has been definitely americanized after your ancestors came to the USA. Do you know from where exactly did they come? Was it in what was called in those times Prussia?
Austin is an English subistute of German name August and its latin version Augustus. As you probably know, many German princes were called August, even couple Polish kings had name August, including 2 of German origin. The Polish substitute for Austin would be similar to the German one - August or Augustyn.