The easiest (and recommended) solution is to get an ADS design kit from the foundry/manufacturer.
If you want to do this yourself, it is possible but you need to have good understanding of ADS. Importing the layout into a new cell (layout view) is easy using standard formats like DXF or Gerber, the difficulty is to create the proper schematic and netlisting views, and make things netlist properly for simulation.
This manual approach is beyond the scope of a forum (too many steps to document if you don't know users' ADS skills), but you might find some writeup in Keysight ADS Knowledge Base (login required). ADS support might also have some documents to show the workflow.