To my knowledge, he was an Arminian, not a Calvinist. He said some shaky things towards the end, things that almost sounded universalist. Nevertheless, I respect his monumental evangelical output and thanked the Lord for him on the day that he died.I don't really like the doctrine myself but there seems to be a spectrum of thought within "Calvinism" and many famous figures such as Billy Graham himself (originally a Presbyterian minister I believe) may have been in this camp.
C.S Lewis was also Arminian but it is not uncommon to hear Calvinists extrapolate from his insights.
John Calvin, as astute as he was, is not the standard. The standard has always been and always will be the Holy Bible.