Youth Gastis played soccer at the high school level in 1987, where he played in the Toronto High School Senior Soccer Championship final with
Danforth Collegiate and Technical Institute and helped them win the title by contributing a goal against
Western Technical-Commercial School. He returned to play with Danforth for the 1988 season. In the summer of 1989, he represented
Team Ontario in the
Canada Games and won the gold medal after recording a goal against
Team Quebec. Gastis would transfer over to
East York Collegiate Institute in 1989. The 1989 season also marked his experience in the professional ranks as he signed an amateur contract with the
North York Rockets of the
Canadian Soccer League.
North York In 1989, he played in the national
Canadian Soccer League on an amateur contract with
North York Rockets. Gastis would appear in 12 matches with North York. He re-signed with North York the following season. In his sophomore year, he assisted the Rockets in securing another playoff berth by finishing fifth in the division. Once more the Rockets were eliminated in the preliminary round by the
Vancouver 86ers. The 1991 season marked his third consecutive year with the organization and he managed to record his first goal against
Kitchener Kickers on August 28, 1991. North York qualified for the postseason for the third consecutive season where he scored a goal in the semi-final round against
Toronto Blizzard. Throughout the season he made 13 appearances and recorded 1 goal. He would help the Wolves claim the league cup and secure a playoff berth by finishing second in the standings. Gastis would appear in the first match of the championship final against
Toronto Italia.
Indoor soccer In the winter of 1995. he played at the
indoor level in the American-based
National Professional Soccer League with
Chicago Power. In total, he played in 3 matches and scored 2 goals. He would play with the expansion side
Toronto Shooting Stars the following year. In his debut season, he would play in 6 matches and recorded 3 goals. == International career ==