My parents have travelled once to canada and twice to USA in last 4 years. They have a 10 year multiple entry visa for USA and already have one single entry visa for Canada. What is the likelihood of getting 5 year multiple entry visa...
You can not actually ask for the number of years/months but you can ask for the multiple entry and pay the corresponding fee. Your parents can get lucky. I have heard of some people being granted 5 years multiple but first hand info, three years- travelled twice to Canada, each time single entry then asked for multiple, was granted three years.