As I have noted in past posts, the connection of this structure with Esther and Mordechai is a tradition. Scholars regard the story in the Book of Esther to be a novel. We have no particular reason to think either protagonist existed outside the story.
But according to this article at least one archaeologist thought that this tomb existed as far back as late antiquity and had a Jewish connection.
The Tomb of Esther and Mordechai (or Mordechai and Esther) has been in the news lately. For past posts, see here and links.
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