That link shows you only how to use the Dedicated GPU (NVidia or AMD card) instead of the integrated GPU (GPU on the Intel CPU - much less performance).
This does not mean that Artlantis is using the GPU instead of the CPU for rendering
The application uses the GPU all the time to display stuff in 3D while you edit materials, change viewpoint, place lights, etc. That does not mean that it is using the GPU specifically when creating the Rendered image.
The application must be specifically written to use the GPU instead of the CPU. This usually results in "real-time" rendering.
For example, OctaneRender is using the GPU for rendering. Look what its wikipedia page says:
Octane Render is a real-time 3D unbiased rendering application that was started by the New Zealand-based company Refractive Software, Ltd and OTOY took over on March 2012. The first non-beta stable version, v1.0, was released on 28 November 2012 and later versions of Octane Render continue to be deployed as a Web release software. It is the first commercially available unbiased renderer to work exclusively on the GPU (Graphics Processing Unit) and has the ability to work in real time. This allows users to modify materials, lighting and render settings “on the fly” because the rendering viewport updates immediately whenever a change is made. Octane Render runs exclusively on Nvidia's CUDA technology (which restricts it to running on video cards from Nvidia) although Octane Render 3.0 is planned to remove this restriction.