The gothic architecture is not a very common subject for architectural visualization these days, unless you work with some kind of restoration. But, if you want to take a look on an example of visualization inspired by gothic architecture made with Blender, just take a few minutes to check out this project created by Mateusz Tulski. The render was all made in YafaRay and at the link you will find lots of settings used by the artist to achieve materials and the overall look of the scene.
But, what if you don`t use YafaRay? There is always something to learn on a project like this, especially on the composition side and material settings.