Sanjay Mishra notes that SQL Server 2016 and 2014 SP2 support UTF-8 for BCP and BULK INSERT:
This requirement has been addressed in SQL Server 2016 (and backported to SQL Server 2014 SP2). To test this, I obtained a UTF-8 dataset from http://www.columbia.edu/~fdc/utf8/. The dataset is translation of the sentence “I can eat glass and it doesn’t hurt me” in several languages. A few lines of sample data are shown here:
(As an aside, it is entirely possible to load Unicode text such as above into SQL Server even without this improvement, as long as the source text file uses a Unicode encoding other than UTF-8.)
I ran into this problem before, where developers wanted to bulk load UTF-8 but had to settle for an inferior solution.