Up to 1918 it was http://users.erols.com/mwhite28/austhung.htm
Your ancestor was NOT from Austria of present but of the above.https://familysearch.org/search
What language was spoken by your ancestor?
What religion Roman Catholic, Byzantine Catholic?
Any US born children ?
Could your ancestor have been from one of these locations :http://www.radixindex.com/en/surnames/surname/forishttp://www.radixindex.com/en/surnames/surname/dudas
Of course, most of those locations are in the new countries that were formed after 1920.
I do find FORIS^ , DUDAS and DUDAS^ in Slovakia .
Do take a look in www.ellisislandrecords.org
just to give you an idea of where the FORIS and FORISZ were arriving from.