BETA is still going, although they are caught up in a scandal involving overpriced contracts for the Correios (Post office). They have one(?) DC-8 and apparently still operate 707s to Porto Alegre (according to the airport site).
The closest I can find to their own site is
http://www.bxbex.com.br/
which lists 4 x 707 as the fleet. I have seen a DC-8 in their colours at Guarulhos recently and
AFAIK their current fleet is 1 x DC-8 and 2 x 707.
Hope that helps