The Premier League club actually received two bids for Pienaar, who is out of contract in the summer and has turned down the offer of a new deal at Goodison Park, but one was knocked back.
Atletico Madrid and Inter Milan are among the clubs to have been linked with the the former Borussia Dortmund, who is though to favour a return to Europe.
Moyes said: "We have had two offers - one of which has been accepted - and we have given permission for his representatives to speak to the club involved."
Asked if Pienaar, 28, would be involved in Sunday's Merseyside derby, Moyes added: "At the moment I would think so."
Everton had reportedly given Pienaar permission to hold talks with Chelsea regarding a potential move to Stamford Bridge, but Blues boss Carlo Ancelotti has denied that he made an approach.
"I read a lot of names in the papers, not just Pienaar but others, there's a lot of speculation. Some agents use our name to earn more money," said the Italian. "I can just say Pienaar is a good player, but that doesn't mean we want Pienaar to play here."
Asked directly if Chelsea made a bid, Ancelotti replied: "No I don't think so."