éʝtsi comes from the prefix eʝ(e)- (< Medieval Greek éðe ‘there’) and the local adverb ecí ‘there’ (with tsitacism) (Kretschmer 1905˙ Giannoulellis 1989˙ Papanis & Papanis 2004).
E.g. tú-vris? éʝtsi íni.
tó-vres? eʝe-ecí íne.
‘Did you find it? There it is’.