In terms of gaming, realistically how much better is the 1080 8gb version than the 1070 8gb? I have a QNIX2710LED screen, refresh rate of 60hz. Any insight would be helpful. Thank you.
There's quite a bit of difference between the GTX 1080 and GTX 1070. Now if you had a 1440p@144Hz monitor, I would definitely recommend the GTX 1080. But since it's a 60Hz monitor, a GTX 1070 will suffice. Go for the GTX 1080 if you plan on upgrading your screen in the near future.
What CPU do you have? It plays an important role too. Anything around the 7600k is a great match.
That depends on the game. But on average I would say it performs about 20-30% better than the 1070. A 1070 should be able to max out the majority of games at 1440p 60fps. However 1070s tend to be on the expensive side at the moment, so depending on what price you can find a 1070 for the 1080 may be the better buy.