He was an influential figure in the modern history of theater in Quebec. In the middle of the 1970s, Gravel, Jean-Pierre Ronfard and Political Pelletier co-founded the Théâtre Expérimental de Montréal (Transmission Electron Microscopy). Later ideological conflicts, led to the foundation of the Nouveau Théâtre Expérimental.
In 1977, Gravel co-founded with Yvon Leduc the highly successful Ligue Nationale d"Improvisation.
He died in Saint-Gabriel-de-Brandon, Quebec.