My parents have a multiple entry US visa. They want to visit relatives in Canada. Do they need to obtain a Canadian visa? They are Indian citizens/passport holders.
Yes. American permanent residents ("green card holders") are exempt from the visa requirement in Canada, but a US visa does not have the same effect.
Yes, Except for visitors who may enter Canada with proof of citizenship, an eTA or a temporary resident visa depending on their nationality, all other temporary residents must hold valid permits while in Canada, which must be applied before arrival, on arrival or after arrival.