Can a company be held liable if they are knowingly supplying another company with products the second company is using to infringe on a patent?

Probably not. The company is doing its own business and is not responsible for "policing' its clients. Patent law is not clear cut in many instances. Which accounts for large corporation defending in court the right to market a product, (they usually win).

Possibly

A patent is infringed by selling components that are combined to infringe the patent. It is called "contributory infringement." The patent owner would need to prove not only that A infringed the patent, but that B sold (or imported) an important special component to A, knowing that it is used primarily in the infringement. Then A and B are both liable. It is sometimes easier to sue only B, the supplier, when there are many end-user infringers, A.Title 35 U.S.C. Section 271(c): "Whoever offers to sell or sells within the United States or imports into the United States a component of a patented machine, manufacture, combination or composition, or a material or apparatus for use in practicing a patented process, constituting a material part of the invention, knowing the same to be especially made or especially adapted for use in an infringement of such patent, and not a staple article or commodity of commerce suitable for substantial noninfringing use, shall be liable as a contributory infringer."

Furthermore, a company may be guilty of an "active inducement to infringe" when it sells a kit for building a patented invention or hires someone to manufacture an infringing product. 35 USC s. 271(b).