Where are you getting the idea that the Dutch Sinterklaas is funadamentally pagan? He may possibly have some pre-Christian elements (Margaret Baker in Discovering Christmas Customs and Folklore argues that the Father Christmas figure is derived partly from Odin), but that's disputable, and certainly not unique to him instead of Santa Claus more generally.

Regardless, Sinterklaas very definitely based on St. Nicholas; the 'sint' element in his name (and of course the 'santa' in 'Santa Claus') is cognate with the English 'saint'. Gifts are often given on the fifth of December, the eve of St. Nicholas' feast day.