As already answered the status message "Your decision has not been reached" is terrible English. As such, we can only guess at its meaning. However there are some common mistakes.
Here's what is wrong with it:
A decision belongs to whoever makes it. It isn't your decision to have your application accepted (if only it was!).
However, it has become common for the word "decision" to be used to describe the result that comes from a decision. One area in which this is common is government administration, where political correctness has influenced terminology in an attempt to try and steer perceptions. For example when someone is paid state benefits (what some countries know as welfare payments) the amount they were given was historically known as an award, but to prevent the perception that people are rewarded for not working it is often referred to as a "decision".
In your case, I believe they are trying to say:
We have not yet reached a decision about your application.
But because they are speaking about a decision on your application they have phrased it (badly) to try and indicate that it the decision you are waiting for.
If I am correct, then this status is still hopeful - it sounds like you are still waiting for a decision, so a decision has not yet been made on your application either way.