In general, you would need to have external server for it, as Roblox doesn’t support IRC.
So let me explain it better:
You would need to code an some webserver, which would have some endpoints: CreateVoteRequest, ReturnVoteResult, ReturnChatRequests
So Roblox Server sends to CreateVoteRequest data with question and variants.
After vote ends, external server checks for vote results by using Twitch API and then waits for Roblox server to access it, also same thing could be happen with chat messages, just checking messages, which matches to it and wait roblox server.
You can use loop check every few seconds for it on script.
In general, it’s not that easy work to do, if you don’t know another programming languages as Node.JS, Python and etc.
I believe twitch uses WebSockets for their chat, so you would have to use an intermediate server.
If you want to keep it simple, you can create an express app with node.js, and tell the viewers to go on an URL to vote. You can use the long-polling technique to return the values to the Roblox server.