Kupka's childhood was spent in Marklowitz (Marklowice), where he and his family (brothers Paul, Johann and Joseph and sister Paula) were active in the Polish-Catholic Association.
An official at a coal mine, he was put forward by Wojciech Korfanty to take over the management of the Organization Division of the Polish Plebiscite Commission in Beuthen.
In September 1920 Theofil Kupka founded the Upper Silesian Plebiscite Committee (Das Oberschlesische Plebiszit-Komitee) in Beuthen.
Initially this committee aimed for "free-state autonomy" (independence) of Upper Silesia and opposed the "corruption" of the Polish Plebiscite Commission.
On 20 November 1920 at about five o’clock in the evening, two members of the Bojówka Polska (Polish Paramilitary Unit) named Myrcik and Jendrzej came to Kupka's house under the pretext of seeking jobs in the mine where he worked as an official.