Short generic answer for all SaaS/cloud: remarkably little. If you're a legit business, who can make payments as a business (rather than on a personal card), and have any small amount of spend, you should have no problem getting a basic contract that provides you some reliability for your business.

Negotiating significant discounts needs a bit more work, commitment, or growth story. Discounts tend to scale with spend.

(Disclaimer, I now happen to work at Google, unrelated to cloud, but this was my experience at my previous employer)

I got decent support from actual human beings for Google Cloud even when spending ~£100/monthly.

Not sure if this has changed recently, but this was in about 2018/2019.