No, according to a Daily Beast article, a spokesperson for House Speaker Mike Johnson clarified (Daily Beast):
When asked to confirm the claim that Trump was an “FBI informant,” a spokesperson for Johnson sent the Daily Beast the following statement: “The Speaker is reiterating what the victims’ attorney said, which is that Donald Trump—who kicked Epstein out of Mar-a-Lago—was the only one more than a decade ago willing to help prosecutors expose Epstein for being a disgusting child predator.”
This statement shifts away from describing Trump as an “FBI informant,” defined as someone who supplies "information to the FBI on a confidential basis" (see FBI.gov), to someone who was “willing to help prosecutors”.
Prosecutors, unlike the FBI, are legal representatives, such as a “lawyer who initiates prosecution of criminal offenses” or, at the federal level, a “U.S. Attorney” who may serve as the prosecutor for federal crimes (see Cornell University).