The only intrigue surrounding Kathie Lee Gifford singing the national anthem at the Super Bowl on Jan. 29 in Miami is whether it will be live or Memorex. Past performances, including Whitney Houston's stirring rendition during the 1991 Gulf War, were prerecorded. ''We encourage performers to have a recorded track they can sing to,'' says Bob Best, pregame show producer, who adds that Gifford has already taped a version of the anthem. ''It's (protection) in case the performer wakes up with a cold. We leave it up to them if they want to sing it live.'' What's Gifford's game plan? The singer would only say, ''I'm prepared to perform the anthem the way the NFL requests me to do it.'' According to Best, the final decision won't be made until the Super day.