I try to view my preview from another angle. Presing wasd in viewport does nothing. Ive also tried the mouse but nothing happens. I can only view it from top down view.
Pgiamos did Orrelakestudios 's comments help? If not, can you please post a screenshot showing your viewport.
Press and hold ALT and the Left mouse button to rotate and move around the terrain. There are some additional navigation options under the Gaea-Preferences tab (in red on my screenshot)