if you save things efficiently, you should have no problems
If you want to check how clogged the request queue for saving is, use this: game:GetService(“DataStoreService”):GetRequestBudgetForRequestType(Enum.DataStoreRequestType.SetIncrementAsync)
Per key there is a limit of 4 MB like mentioned. But per actual data store it is basically infinite, so you could have infinite keys. At least until Roblox can’t afford paying for data store usage but I doubt that will happen anytime soon. But I still wouldn’t take advantage of that.
What is your use case for wanting to store gigabytes/terabytes of data??? lol
Do you mean how much stuff can you load in before it crashes? If you are having trouble with that you need to make your game more efficient. I don’t know the limit, but you NEED to think about optimizations before you do this.