Gold electroplating is the process of using electrical current to coat a base metal with a relatively thin layer of gold. The thickness of the layer is 5-20 microns.
A closer examination of the Rolex Submariner 16613 clasp will show that the actual clasp is not electroplated. The layer of gold is substantially thicker - my estimate is 0.5 - 0.8 mm (500-800 microns) In essence, what we have here is a thin sheet of solid 18K gold fused at high temperature to the steel clasp.
Under normal 'wear and tear' condition, a 16613 clasp would probably need some light to medium polishing once every 3-4 years. My guess is that the gold layer would be substantially worn or even completely worn out after 5 polishing cycles or approx. 20 years. I have personally polished a number of clasps already with no visible abrasion to gold layer.
On the contrary, electroplated surfaces should not be polished. Even a very light buffing will remove gold plated deposit and expose the base metal.