Basically, a person can file for unemployment benefits as long as they are fired or laid-off. If he quits voluntarily, it becomes more difficult and is more likely to be denied, so make sure he finishes his expected time with the company.
Now, there are reasons for an unemployment claim to be denied because a person was fired, but those reasons are generally because the employee was terminated for misconduct (stealing, failing a drug test, insubordination, etc.). Since he is being fired because the company decided he wasn't a good fit because his skills no longer matched their expectations (which is my take on it), he should be able to collect benefits. Also, as long as he has worked for the company long enough to make the minimum required earnings, he should be able to file for benefits. The time and earnings vary from state to state, so definitely check the unemployment office website for your state.
There is always a chance that the employer could deny his unemployment benefits. Unfortunately, some employers deny benefits no matter what, even if the employee is right to file them. If this happens, he should file an immediate appeal. Your state will advise him of his appeal rights, and there will be a specified time frame in which he must file his appeal. Now, if this does happen, the employer will be required to prove with documentation that he was fired for something that was his fault (misconduct, etc.). Tell him to keep every piece of documentation that he has from the employer (termination documents, any warnings he received from the employer, etc.) to use in case he has to file an appeal.
Here is a link that provides the unemployment offices for each state. Just click on your state in the list, and it should take you right there.
I hope that answered your question. If you have further questions, please ask. It's been my pleasure helping you. Please remember to rate my answer positively, as rating me is the only way I receive credit for my work.