Yes and no. You can't copy neither Layouts nor Layers from inside Construct 2. But, if you save your projects as project folders (instead of being saved into one capx file, every project will be a folder filled with all the project files), then you can copy-paste the Layouts and Event sheets .xml files from one Project to another. Just make sure that all the objects that appear in those Layouts and Event sheets exist in both Projects prior to copying the .xml files (or Construct will show an error message).
It works, I've been doing it a lot lately.