Recently purchased the Samsung 970 Pro (512GB) and installed.  Put my video card back into the PCI slot above the M.2 slot where it was before so I could keep my I/O panel the same without removing additional spacers and such.  Using a DG-87 case with this build.  Installed the OS onto the m.2 SSD and completed updates, etc.  My question, with my video card sitting directly on top of the M.2 module placement, would this generate too much heat for the m.2 drive?
 
Video card:  EVGA Geforce GTX 1070ti
x99 FTW K
 

It shouldn't, though I always recommend downloading a hardware monitoring software that provides temp readouts of your drives so you can observe. The 970 Pro has an over-temperature protection, so it will throttle it's speed if running too hot, though of course you would want to try to prevent that from happening. Its reported operating temps are 0-70c(https://s3.ap-northeast-2.amazonaws.com/global.semi.static/Samsung_NVMe_SSD_970_PRO_Data_Sheet_Rev.1.0.pdf). There are also thermal pads for NVMe drives available to assist with heat as well.
 
Best,
Alan
EVGA

If you should run into any temp issues, there are some heatsinks kits you can apply, as long as the measurements are done properly. 
 
I personally performed a DIY before these heatsink kits were out and added some Fuji pads and some short heatsinks on it.  Haven't had any issues.