Ohh so then what can I do to prove that I can support him ?Unfortunately, the visa office still looks at his ability to pay for his own trip - they cannot have a guarantee from you that you will pay his expenses and therefore he has to qualify on his own for travel.
If he has no establishment in Jamaica and a family member willing to care for him in Canada, the visa officer's concerns will be that he will come to Canada and refuse to leave, likely applying for H&C considerations to stay.