There are $3/5/10/20 tiers. $3 will get you the vast majority of the benefits (previews and polls every 2-3 days), higher tiers have higher vote weights and (in the case of $10/20) get access to beta builds to test new systems and help me find bugs.
They all get access to a patron channel on discord where I post more screenshots and get feedback as well.
In general, I try not to make Patreon rewards TOO good, but it's how I fund basically everything about the game since itch doesn't help much there.