Have the two events ever been simultaneous?
No, this has never happened.
Until 2002, the Super Bowl was always played in January, and the Winter Olympics almost always begins in February. Now that the Super Bowl is played in February, the events are closer. Since 2002, the Winter Olympic Opening Ceremonies has been scheduled for a Friday, and the Super Bowl is always scheduled for Sunday. In addition, since both the Super Bowl and the Olympic Opening Ceremonies are worldwide television events, it is unlikely that they would ever schedule both events for the same day.
This year, with the Super Bowl on February 2, 2014, and the Sochi Opening Ceremonies taking place on February 7, the two events are as close as they have ever been, although they were just as close in 2002, when the two events occurred on February 3 and February 8.