Topography in Revit can be tricky to manage for a number of reasons, but I would say the most limiting factor is that you can only input points (meaning, you cannot input contour lines or a mesh). If you do use a mesh or 3D lines to create a Topo, Revit simply takes the points from those elements and gives you no control in the generated mesh and contours.
This can be fairly frustrating, particularly if you are accustomed to Civil 3D, where you have control over these elements. Unfortunately, this is an issue that is hard-coded into Revit Topos, so until Autodesk decides to fix the Revit surface engine there isn’t much you can do (besides use other elements, which can be a partial solution).
Once the Topo is generated, you can extract the contour lines and underlying mesh elements by exporting a 3D view to dwg. And with Dynamo, you can extract all three Topo elements (points, contour lines, and mesh) entirely within Revit.
landarchBIM 