Gabriel Eliasson was born in Kungsbacka, Sweden.
Eliasson played amateur hockey for Kungsbacka in the U16 league. In 2020-2021, he played in five games and tallied one goal and five assists. He got more ice time in 2021-2022 and scored three goals and nine assists in 26 games.
He played for HV71 in Sweden's U18 league in 2022-2023. He suited up for 37 games and scored one goal and seven assists. This past season for HV71, Eliasson played in 36 games and had one goal and five assists playing in the Jr. league.