Here is the link to the article:

Dwg Import – Lines Nearly Vertical/Horizontal are Changed, from Steve Stafford’s blog

The answer is YES!  Revit does have an origin, if you try to draw a cross at the origin in AutoCAD and import the file into Revit (in the dialog box, check the box next to Link*, and under Positioning, select Auto – Origin to Origin), you will see where the origin is.  Knowing the origin location is specially important if you are trying to import several levels of floor plans, site plan, etc., into the model.

Here are 2 useful articles if you want to learn more:

• Starting You Revit Model from a 2D AutoCAD Draiwng – Step by step instruction on how to import a dwg into Revit and model from it, from CADuzer
• Shared Coordinates in Revit (and AutoCAD) – import DWG file into Revit with Coordinate System, from CADuzer

Link*

Link box checked- Your CAD file in your Revit model will be updated every time you make changes to it.  You can view your entire list of imported cad files under File > Link Manager

Link box unchecked – The CAD file is inserted into the model instead of linked.  All changes you made to the CAD file will not be updated.  You will have to remove and reinsert the file for the updates.