GPU requirements

I’m currently running a 6th generation I5 with 8GB’s of RAM, will this paired with an Nvidia GTX 950 be able to run the engine without incident or is a more powerful GPU required??

It should be enough to run the Editor and look at Content Examples, I think. “The engine”, if by that you mean your game, that is up to you: it depends how much you will be rendering on screen, how large your scenes will be, how complex your shaders are, etc.

UE4’s FAQ (found here) states:

For developing with UE4, we recommend a desktop PC with Windows 7 64-bit or a Mac with Mac OS X 10.9.2 or later, 8 GB RAM and a quad-core Intel or AMD processor, and a DX11 compatible video card. UE4 will run on desktops and laptops below these recommendations, but performance may be limited.

Well as far as shaders are concerned I’m not doing anything much more complex than that in the content examples and my scenes are fairly simple, mostly low-poly trees and foilage and small landscapes. And by taking into account that my PC at this point runs almost smoothly on integrated graphics, I figure not much more power is needed, at least not for my current plans.

Then you’ll be fine. If you dont’t run the game in full debug (with the full source code), you’re limited by what you put in your game if the basics, like the Editor, run fine.