This classy tutorial examines the procedure of not only creating curved stairs but curve railings and modern stairs also. What you need for this tutorial is the basic understanding of Revit and its execution methodology.
This tutorial is created with the latest version of Autodesk Revit.
Initially you will need to set up the entire interface of Revit to make it work. And then you need to select the tool which would be preferable for you to use such as from stair tool you can select either Stair by Component or Stair by Sketch.
In this way you can create your desired output of curved staircase.
For more information, watch the video.