Can i submit my current project??

Actually, its demo has been released, but as i tend to keep on adding new features in it, so can i submit it for the jam, after its October update??

Based on the rules, you are allowed to submit games that you already made and you can add new features while in the Devtober period which you will submit. I think you can't submit it after the challenge's period. Just post it on itch.io on the deadline and then you can add more features after it.

As Takago said, you absolutely can!

If anything, I'd say it's even recommended, the whole point of Devtober is to just work on something, so having an existing project is probably gonna make things feel less daunting. You're setting yourself up for better results that way! 👍