我想去加拿大旅遊逗留最長時間幾耐,因為想去朋友度往下。?

It depends on the Government of Canada and you.

With eTA, a HKSAR Passport holder can travel to Canada visa-free for up to 6 months (Note - it is not necessary that Canada will let you stay the entire 6 months).

However, if you have adequate documentation and financial resources, you can apply for a temporary resident visa, which can further extend your stay.

持特區護照最長可停留加拿大 6個月。