It can be tricky trying to read another person, but a little of that is what you're going to have to do if you're ever going to know if there's a real chance to get him back.
Figuring out how your ex feels about you so you know what your odds are can be a difficult task that blocks a lot of people seeking their exes back, but there is a way that's not too difficult and pretty reliable.
It's all a matter of how your ex appears to consider the idea of being in contact with you, and you can read this by analyzing how willing he's been to talk to you after the breakup...
particularly via phone calls and messages left.
If he's been reluctant to return your calls and hasn't made any effort to contact you himself...
chances are he's trying to or already has gotten over you, and is moving on with his life.
In this case, things aren't too bright for you but it's not always the end...
I've seen plenty of couples actually make it past this stage of the game.
A more positive situation, however, is if he seems quite open to the idea of still having you in his life.
This can be shown by a willingness to return your calls, or a track record of making his own attempts to contact you.
This demonstrates that he definitely still has feelings for you, even if they may not be as strong as they once were.
Even if he's not sure he still loves you, the seed is there if he still values having you in his life.
This is a far better starting-off point to get him back, though it'll still take some work.