He actually did say he was going to pay for it personally, the military might cover some component of it, but it's in the article saying that he couldn't reimburse the family through the government:
Natalie Khawam, the family’s attorney, responded, “I think the military will be paying—taking care of it.” Trump replied, “Good. They’ll do a military. That’s good. If you need help, I’ll help you out.” Later, a reporter covering the meeting asked Trump, “Have you offered to do that for other families before?” Trump responded, “I have. I have. Personally. I have to do it personally. I can’t do it through government.” The reporter then asked: “So you’ve written checks to help for other families before this?” Trump turned to the family, still present, and said, “I have, I have, because some families need help … Maybe you don’t need help, from a financial standpoint. I have no idea what—I just think it’s a horrific thing that happened. And if you did need help, I’m going to—I’ll be there to help you.”