What is known is the Eccleston had met 2 or 3 times with Moffat.
That isn't really "known." Someone associated with the show apparently told Digital Spy it had happened, but that doesn't necessarily make it true. Granting for the sake of argument that it is, though, as Allyn says there's still no reason to suppose there was a draft, or even a written outline, at that stage. In the meetings Moffat would have described as much plot as he had worked out, with special reference to the ninth Doctor's role, and Eccleston would have responded to that. Does this mean that there was a 50th anniversary concept in existence with room for three Doctors? Sure. But there was also another plan for the more likely event of Eccleston saying no, and I very much doubt that that plan was "replace him with a Doctor perhaps 50,000 people have any attachment to."
Besides, the special is in production now. McGann may joke about getting called on two days' notice, but by this point he (or one of the others) would certainly have heard if he was going to have a meaningful role in the special, the kind of role that would originally have been filled by Eccleston. Either the classic Doctors are all fibbing, or they're going to be called soonish for cameos, or they're not in the special at all.
Yes, there are. Ta
bloids had claimed that Eccleston agreed to participate but then pulled out right before the start of filming, which is what prompted Digital Spy's source to make the counter-claim that is now being treated, a bit prematurely, as confirmed fact.