After serving his mandatory military service in the Israeli Defense Forces he studied theater and psychology at the Tel Aviv University.
During his childhood he immigrated together with his family to Israel. After graduating he began playing in the Khan Theater in Michael Alfreds group. Afterwards he played in several stage productions at the Hacameri Theater, the Be"er Sheva Theater and the Beit Lessin Theater, in which he currently is one of the permanent staff
Among the many plays he participated in were "Servant of Two Masters", "Catch 22", "Who"s Afraid Of Virginia Woolf?", and "Rain Manitoba".
Gabai also played in the 1989 children"s musical "Peter Pan" as Captain Hook. Through the years Gabai also played in the various productions in the Israeli television
Among others he played in series "The Haim Neighborhood" (שכונת חיים), "Siton" (סיטון), "Late Night Stories" (סיפורים לשעת לילה מאוחרת), and in the drama series "The Kastner Trial" (משפט קסטנר) in which he played Rudolf Kastner, he was a host in the comedy series "Zehu Ze!", and played a cameo role in the popular comedy series "Krovim Krovim", in addition to many other productions. Gabai resides in Tel Aviv, is married and has five children.
In 2008 he played the role of Ahmed Hassan al-Bakr in the American television mini-series "House of Saddam".
In 2011 he played the lead role in a film "Restoration", a role for which he was nominated for an Ophir Award.