The rumor was 200+ pilots but that number is quite optimistic at best to say the least. A former Varig captain that flew at Ryanair for 2 months went returned to South America to fly with TAM. That is the airline to which the bulk of the former Varig pilots are flocking to. Some are going to another South American carrier... I beleive it's called GOL.
The ones that do come over will probably work under an IAA validation certificate which will be obtained through normal means.