No, generally, it's not possible to link information between layers using rules (when there are rules in both layers).
In specific cases, it is possible to pass information between layers. For example, if you have information that is not generated by rules, then you can connect rule attributes to other attributes from other layers (Inspector -> click on drop down next to attribute -> Connect Attribute). If you have an image/map that shows distances to public transportation stops, for example, then you can connect a rule attribute to this map and get the distance to public transport. This is similar to what is done with building heights in Tutorial 3, section Control the Skyline.
Tutorial 3: Map control—CityEngine Tutorials | ArcGIS Desktop
If you have a rule that calculates the total GFA in layer B, then a two-pass approach would be needed to get that information into the rules applied to shapes in layer A. I don't think there's a nice solution to this problem yet. I think maybe others might use Python to help with the two pass generation (?).
We are working on methods that might help with calculating distances to other shapes, so hopefully this will be possible in the future.
