How many 1913 liberty v nickels were originally minted?

No one knows for sure since they weren't officially produced for currency, at most 5 or 6 pieces.

There are 5 known pieces, the whereabouts are known on all of them.

There is a possible 6th specimen known as the Walton specimen, the whereabouts are pure speculation. It is possible it might be floating around there, or the heirs of Walton may still have it. But it is anyone's guess.