Its debatable if evander would have survived or not(if Lane hafnt stepped in) because evander had remarkable resiliency and recovery powers but it would have badly damaged his legacy if cooper had stopped him right there.
The rules define a knockdown as "any part of the body other than the feet touching the canvas following a punch" There is no caveat for someone being held up by the ropes. For example, in Ali-Foreman Big George nailed Ali on many occasions where he careened back against the ropes. "But For" the ropes, he would have been knocked out of the ring. Yet, nobody considers those to be worthy of a "knockdown" (and rightly so). Holyfield did indeed have excellent recuperative powers, so it is certainly possible he would have regained his senses regardless of the 10 second respite Mills Lane gave him. But, make no mistake, Holyfield was hurt. And if Cooper had landed another shot on the defenseless Holyfield, he may have been knocked out. And, there was nothing within the rules that allowed Mills Lane to stop the action and keep Cooper off of him. And, Mills Lane knows it.
http://fromthevault.hbo.com/holyfieldcooper This article is a long one. But, a great read. Boxing stories rarely get crazier than the life of Smokin Bert.
Except for his knee touching the canvas...which happened when Holyfield careened into the ropes. Even if that wasn't the case, the official can rule that if a fighter would have gone down had it not been for the ropes, a knockdown is scored and a count is given. That's been true for a while.