On the page you have applied file upload, go to the bindings panel, On the bindings panel there is a Binding group for each file upload called WA Uploaded Files (Fiel Field Name) Where file field name is the name of the file field.
in this binding group is a binding called Server File name.
Add this binding to your page and copy the code, then past this binding code into the email template where you would like to show the uploaded file name.