How to print a whitespace when a field is not filled?

When a client does not choose a field, how can I print out their entry with a blank space where the response should be instead a void

In the Submissions Page, click on the Settings and uncheck the Auto Hide Empty Fields option.

https://www.jotform.com/help/269-How-to-View-Form-Submissions

If you want to do the same on the PDF Document, uncheck the same option while you are on the PDF editor. It's under the Customize Tab as seen below: