The 980ti and 1070 are very close, close enough that statements about which one is better is kinda irrelivent, its in the sub 2-3% depending upon the style of bench or not.
There are no 10 series cards that are better than even the base 980 for that matter other than the 1070 or better. And again its basically 8-10% difference, and that doesn't directly translate into frame rates since the cards are almost never actually 100% loaded, cycle for cycle,
I was running a 980 in a super old PC with a 2.8GHz Core2Quad... I got a constant 60fps out in space, would drop to around 50 in station and on surface. The fact that changing settings to low on that computer had no effect on frame rate, meant that the Mobo or CPU was the throttling factor.