The 25-year-old has long-since been one of the most coveted strikers in world football and 16 goals in 21 appearances across all competitions this season has seen his value continue to rise.
More offers have seemingly arrived for the France international, but Lyon will continue to fend off interest in Lacazette, Aulas said.
"It is true that the offers we have received for Alexandre range from €40m - from West Ham last year - to €70m right now," Aulas told RMC.
"Obviously, Alexandre is indispensable for us. Just like Nabil [Fekir] and Corentin [Tolisso] and all the other players for whom we have received offers. We have six or seven offers on the table for our best players.
"We have the intention to close the gap with the teams at the top of the table in Ligue 1 and to go far in the Europa League because this could be an opportunity for us."
Aulas also claims that Serie A champion Juventus has made an approach for midfielder Tolisso.
"There has been contact with Juventus, but nothing is happening this winter," Aulas said.
"We have not made any commitments for the summer, but it is true that Juventus have followed up their interest."