This kind of pilot can be very beneficial. I have some experience with this, and will share some thoughts:
Treat the pilot as a stand-alone business opportunity. I understand the excitement of the possible venture funding tie-in, the benefit of being able to reference a big company, etc. But each of these is a separate facet of the relationship that should be thought about (and negotiated, and agreed to) separately.
With respect to the specific pilot, you say that it is a pilot with a client of the Fortune 500. Especially if they are reselling your product, but even if they are just referring the client to you, they will be concerned that that you and your product doesn't jeopardize their relationship with their client. Be sensitive to that, and take whatever steps you can to mitigate that concern (such as collaboration on deployment, regular status updates back to the Fortune 500, etc.)
I would aim not to discount your pricing for the pilot unless demanded of you--and even then, would consider carefully before agreeing to discounts. Besides piloting your solution, you want to also pilot your pricing, your terms and conditions, your client on-boarding, your deployment, etc.
If the client or the Fortune 500 tries to suggest that you should discount because the product is new, is unproven, etc. I'd try to find other ways to mitigate those concerns: reduced pricing doesn't really mitigate those concerns, and in fact can reduce your viability (because you need money). Instead, I'd communicate that you want to professionally support the client in a way that exceeds expectations, and that while you are excited about possible future synergies, you need to do what is in the best interest of your business so that you can be sure that you have the resources you need to provide excellent services. Reasonable clients / partners will want to see you be successful. And you don't need / can't afford unreasonable clients / partners--no matter what their name is.
You should not consider working for scraps, as that will jeopardize your ability to successfully meet and exceed expectations. It is in no one's interest that you fail. If your pricing is reasonable, nobody should object. If your pricing is not reasonable, then you have a systemic problem with your business plan that you need to address immediately. If needed, offer up other incentives besides reducing price: Pay full price, lock in this pricing for the future. Or get X hours of priority support at no charge. Or at worst, buy now, get year 2 at 50% off, etc.
The best way to use the pilot to further dialog with the venture arm is to succeed in the pilot. Go do the pilot, be successful with it, and then go to the venture arm with that gold star in hand.
All of that said...you need to earnestly consider whether you and your product are ready for the pilot--apart from any funding considerations. You don't want / can't afford to fail in delivering what you are promising. If you have any doubts about your ability to deliver right now, defer the pilot until you are ready. But be transparent about that--because perhaps the client or the Fortune 500 can help: "We want to hold off on the pilot until we have our new server infrastructure in place, and we are currently raising funding for that."...might lead to discussions about ways to run on their servers, etc. (just as a hypothetical example).
Also, remember that supporting the pilot will require time and resources--that will compete for time and resources needed by the rest of your business (raising capital, continuing with development, etc.) Besides reinforcing what I said above about the pilot needing to be a "real" revenue-producing deal, be sure you have the resources in place to be successful. But just as important, be sure that the pilot deal is not a distraction.
What I mean is: if you're product is aimed at small-to-mid businesses, supporting the Fortune 500 may not really be a stepping stone to long-term success, and may actually slow down your progress. Or, at least taking on this pilot may force you to alter course.
All that to say: treat the pilot like a real business deal on its own, and plan accordingly.