Originally Posted by
Askani's Flame
I was mistaken, it was actually Joe Pruett's run. Cable #71, with pencils by Rob Liefeld.
If you remember in Days of Future Past, when Franklin makes Banshee-811, he remarks that he believed Cable was in Madripoor - establishing that a version of Cable did exist in Earth-811. The future portion of this issue is set after the future action of Days of Future Past but before Days of Future Present, so it's reasonable to believe that Cable defected to Ahab's side by then (hence the "see someone you recognize" comment).
As for how Cable exists in Earth-811, the way I see it is like this:
* The X-Men prevent Senator Kelly's assassination in 1983
* Nathan Summers is born in 1984
* Nathan Summers goes to the future in 1985
* Nathan Summers becomes Cable, fights Apocalypse in the future and decides to time travel
* Cable arrives in the past of 1961 and lives all the way through to 1983
* In one stream of time, the X-Men prevent Senator Kelly's assassination and the loop goes on
* In the other stream of time, the X-Men fail to prevent Senator Kelly's assassination and it becomes Earth-811
So, by way of being a time traveler and going back before the divergence and not time traveling ahead of it, Cable existed during the divergence and an alternate 811-version of him was created by it.