I applied for a visit visa to America and gained it. If I go to the Canadian Border after arriving at America and seek refuge in Canada, will they grant it to me or not??
The Canada-US Safe Third Country Agreement generally means that you must apply for refugee status in the first country (out of the US and Canada) that you arrive in. So since you arrived in the US, and you try to cross the border to Canada and apply for refugee status, this generally means they will turn you back.
However, this agreement only applies if you try to cross the border through a legal port of entry. If you cross through an illegal border crossing, e.g. Roxham Road, the agreement doesn't apply, and Canada will process your refugee application even though you arrived in the US first.
So many people cross at Roxham Road to take advantage of its illegal border crossing status that some taxi companies even drive people right to the end of that road so they can cross, and the Canadian government has built a makeshift refugee camp and reception center on the other side to handle the volume.
To enter Canada as a refugee, you must be referred. The United Nations Refugee Agency (UNHCR), a designated referral organization, or a private sponsorship group can refer you. You cannot apply directly as a refugee. https://www.canada.ca/en/immigration-refugees-citizenship/services/refugees/help-outside-canada.html