Evolution makes predictions about what should be found. Therefore it can be tested. It is an emprical science, as much as geology, cosmology, and archeology are.
In as much as Evolution merely predicts the rate of change in life forms I will grant that it is an empirical science and subject to testing. However, Evolution is more and purports to present an explanation of why and how that change takes place. This part of the study is not testable nor observable, therefore this part of the theory, random mutation coupled with survival of the fittest, is not an empirical science. It is only conjecture, scientific conjecture perhaps, but only conjecture nonetheless.