Is it ethical/ correct to cite a confidential document/ paper (under NDA)?
If the information you want to disclose is contained in a document that is covered under a non-disclosure agreement with the industry partner, you will need to get their written permission to disclose the content that you're referencing at the very least. If I were reviewing your article, and this reference were key, and the company had never published this document, I would be inclined to make negative comments in my review about the lack of publication of a key reference which might lead to the rejection of your article. You might have to work hard to convince your industry partner to either publish the information from the confidential document in a separate, smaller format, or to publish the confidential document in its entirety in order to get your article published. 

Either way, if you rely on NDA materials, you still have to cite them. It'll be best for your publication chances if the company discloses this information itself before you try to publish. Otherwise, even submitting your work to a journal or conference will require permission from the company since submission will count as disclosure.