In Revit 2012, If you are utilizing the 360 cloud rendering tool from the subscription center there are a few pre-settings that you need to adjust before rendering.
It is very important to run a test render inside the Revit software before you utilize the "Render in Cloud" tool.
If you want to utilize your artificial lights you will need to adjust them inside Revit first using the Render settings, then save the file. Now from the Online tab on your ribbon click on "Render in Cloud"
If you run into an exposure issue you can adjust this on the Autodesk 360 website after the rendering has been completed.
If you hover your cursor over the rendering images thumb nail you will see an arrow. Click on it and then click on adjust exposure.
NOTE: from the Help FAQ: Exposure Adjustment works only on WebGL enabled browsers like Google Chrome and Mozilla Firefox. Make sure your browser, video drivers, and hardware fully support WebGL to use this feature.