How long has it been since you filed the claim? Have you submitted the weekly or bi weekly certification for benefits at the end of each week that has passed since you filed the claim? Then they would, if you are approved, pay you for each week after the first one that has passed, AFTER your decision to approve/not approve has been made. The first decision, which may take two or three weeks at best, more if it is contested, will be the initial decision.
When you file a claim for benefits, you are asked the specific reason why you are not working for the employer any more. If you have been terminated, you'll be asked certain specific questions about what you were told when you were terminated about why you were terminated. you'll be asked if you had been warned about this issue, what had been the final incident, etc.
Then regardless of what you tell them, they also check with the employer and ask them exactly what the reason is that this person is terminated. They will say, "Jane Doe says she was terminated for poor performance on June 11, is this correct? What were the circumstances under which.... and Were there any warnings etc.
It will not surprise them a bit if the stories are a bit different. The employer must show, in a termination, that they had a valid misconduct work related reason to terminate the employee or they will be likely to be approved for benefits. In performance issues, they must show that you knew how to do the job, were able to do the job, and CHOSE deliberately not to do the job as they asked to you. If you spent your time at work sleeping under your desk, that is genuine poor performance misconduct and you probably will not be able to get approved. If you showed up, tried hard, and were not able to perform the job, though you tried, that isn't misconduct and you have a good chance of approval.
But the office has to make a decision. They'll talk to you, they'll talk to the employer. Sometimes they'll do what they call a "fact finding hearing," which is usually a call where both parties are on the line and they ask questions. Just answer them to the best of your ability. Always try to work in that you did your job to the best of your abilities.
While the employer may tell the unemployment office something different than you do, and you are telling the truth, just tell your story and do not worry about refuting their arguments or straightening out their story. Just keep your story the same and tell it calmly, respectfully and briefly. Do not get sidetracked, do not give too much detail, do not argue, just state what happened quietly and clearly.
If you are approved in the initial decision, the employer may file a second appeal, and this time there will be a hearing with both parties present or on the phone. If you are denied in the initial decision, you can file an appeal and have another hearing. You will just have to wait and see how the first decision comes out.