In the 'Study Design' page, it is possible to copy entire forms, including all fields that are within the selected form. More information on how to do this can be found in the article: Copying forms.
When copying forms, you have the ability to choose where in the study to copy to. It is possible to 'cross-copy' forms between studies, repeating data and surveys.
Visits cannot be copied directly, but it is possible to duplicate an entire visit by exporting the visit and importing it again into your study.