I have asked this question at the travel agency but did not get a confirmation. My husband has a valid Canadian multiple-entry V1 visa in his passport (Cuba) valid until 2021. Does this mean he can travel to Canada as many times as we want without any additional documents? Is the eTA still needed?
An eTA is only needed if you are visa-exempt (Americans excepted; they don't need them at all). Because you have a valid visa, you will not need an eTA.