Yes!
If you bought the game for $10, then you will receive the next update on the day of release.
If you bought the game for $5, then you will receive the next update when it costs $5.
P.S. I wouldn't mind paying the difference, but itch doesn't seem to let one do that. So I'm left here feeling kinda cheated, because I thought I bought the full package at a discount, but now the only options seem to be to wait or pay "full price" again. Still, love the game, wouldn't be writing this otherwise.
At the time of the release of the new version of the game - it costs $10.
0.8a is out recently and will cost $10 for 1-2 weeks. You paid $5 - not for early access, but for getting a new version. You will receive it, but after a while (until April 15). Those who paid $10 get early access (the latest version of the game at the time of release).