2006-2010 studied at the Lithuanian Academy of Music and Theater, completed the acting study program and received an actor education. 2010-2022 J. Čepulis worked in Panevėžys as an actor of the Juoz Miltinis Drama Theater.On the stage of Panevėžys, J. Čepulis created about 30 roles in performances of various genres. Among them - "Korika" John Ruth (A. Špilevoj "St. Speig", 2022), Nikolai Gogol (N. Gogol "The Cloak", 2021), Gustav Jensen (I. Vyrypajev "The Iranian Conference", 2020), Prisoner, former rebel, later adjutant (S. Mrožek "Provocateurs", 2019), Pranas (A. Škėma "Pabudimas" 2018), Miloš (B. Hrabal "Stop", 2017), Akops Terteraantas (A. Cagareli "Chanuma", 2017 ), A young man (T. Džiuženoglu "Lavina", 2016), Jakob Rundis, a young scum (L. Ruohonen "Cherry in chocolate", 2016), The author (A. Chekhov "Rothschild's violin", 2014) and many others.J. Čepulis created the main role of Mindaugas in the contemporary theater performance of the Palace of the Grand Duchy of Lithuania based on Justin Marcinkevičius' drama "Mindaugas" (2017).For his role in the play "Iranian Conference" at the XI Dalia Tamulevičiūtė Professional Theater Festival in Varėna, he received a prize established by D. Tamulevičiūtė's relatives (together with other actors of the play, 2021) and a nomination for the Golden Cross of the Stage in the "Actors' Ensemble" category.