One higher executive (Oliver Schmidt) has pleaded guilty and is awaiting sentencing. The others are German citizens living in Germany and can't be extradited.
https://www.nytimes.com/2017/08/04/business/volkswagen-diese...
https://www.nytimes.com/2017/08/04/business/volkswagen-diese...
Keep in mind that Assange is essentially the head of a news organization, and famous himself (in a related fashion). He can say both facts and opinions and they will be picked up and carried by others without checking the veracity or likelihood of being true because of his celebrity. Additionally, people will exaggerate his claims based on their own agendas. It's worth looking into the situation before accepting his take on it, or even that of his supporters, verbatim.