Does using Eldritch Smite with a 5th level slot get you an extra 6d8 force damage?

I just have a quick question about Eldritch Smite in Xanathar’s guide. Does using Eldritch Smite with a 5th level slot get you an extra 6d8 force damage or an extra 5d8? 6d8

— Jeremy Crawford (@JeremyECrawford) April 23, 2018