This is conjecture, but I would believe that the amount of creep life left would be a function of both creep life expended and number of cycles spent, and that number of cycles left would also be a function of creep life expended and number of cycles spent.

Both are likely acting in tandem in actively destroying your metal.

But without the lab equipment and materials needed to find fatigue curves at various temperatures and times, it'd be difficult to correlate the two.