Since all RVs of model have a test value, you could use that to get its shape:
model.test_point['β(soc_dem, edu spend)'].shape
Not sure if that is what you are looking for but I also do not know how to debug the theano compute graph efficiently.
Edit: As @junpenglao points out, you can get the shape even more conveniently with the python variable through beta.tag.test_value.shape.