While the CRS [Commercial Resupply Services] contract with NASA is based on a service-delivery model, NASA and Orbital structured it so that Orbital receives milestone payments tied to launches. It is not uncommon in launch contracts to make “intentional ignition” a milestone that, for example, signals the end of one contractual relationship and the beginning of another — even if ignition and liftoff are followed by explosion and failure.
The CRS contracts have two milestones: "intentional ignition", and a successful mission. Orbital is therefore entitled to a payment for completion of the first milestone. It's not clear how much that payment is. The article also mentions that Orbital was insured for the full amount of the second milestone, to the tune of US$48M. As such, the direct revenue impact of the failure to Orbital is essentially nothing. Looks like Orbital's contract lawyers and business continuity planners earned their keep on this one.
Meanwhile, Orbital announced [spacenews.com] this week that it has contracted with United Launch Alliance for an Atlas V launch to carry the next Cygnus cargo spacecraft to the ISS. The ULA contract reportedly has an option for a second Atlas V if necessary to completely bridge the gap until the Antares return-to-flight launch.