The Vickrey-Clarke-Groves Auction is an example of incentive compatible (truthful reporting) multiunit auction, but it is only maximizing social utility, not the seller's utility.
If my understanding of the revelation principle is correct, if we can implement a mechanism that maximizes the seller's revenue in a multiunit auction, then there should be a incentive compatible mechanism with the same payoffs. In the case of social utility maximization, this equivalent mechanism is the VCG auction. But what about revenues maximization? Is there a truthful mecanism to implement such an auction?
Yes. The revelation principle states that if there is a social choice function that can be implemented by some mechanism (i.e., if that mechanism has an equilibrium outcome that corresponds to the outcome of the social choice function), then there is a direct mechanism that also implements that choice function.
Hence, if there exists an auction (mechanism) that is seller revenue maximizing, then there is also a direct mechanism has this revenue maximizing outcome and all players would truthfully reveal their types in equilibrium of that mechanism (here: buyers would reveal their willingness to pay).
About optimal auctions: I think this literature started with Myerson 1981 - Optimal Auction Design, and there is much more to follow this up. One thing to note is that these optimal seller auctions typically do not have equilibria in dominant strategies (which VCG does). Still, there is a direct mechanism that implements the same outcome.