what are the chances of getting a tourist visa to USA, if one have a valid Canadian TRV? does chances increase or remain the same?
Irrelevant , USA Visa is a bit different from the Canadian one. It is by law that the Visa officer considers every applicant as a suspected immigrant until convinced of the opposite.
They look for two major factors : enough money to cover your stay in the US and a strong reason that you will go back to your home country : leaving wife , children, high paying job, etc...
However , if you have a Canadian PR then it would be relatively easy.