Clearly the president gained. As more and more such information dribbles out bit by bit, the public is less likely to put it all together and connect the dots that create the big picture. Had we heard none of the testimony in the Paula Jones case over the past months and suddenly saw it all, with all the connections made, it would obviously have had more impact. The leaks about the Whitewater investigation show the same pattern. Things that are virtually certain to come out eventually, whether in court or in impeachment hearings, are being leaked out in bits and dabs.
Leaks obviously come from someone with something to gain by leaking.
The grand jury testimony is known to many people besides the special prosecutor and the grand jury, who are the only ones forbidden by law from revealing what went on in the grand jury room. All the witnesses can talk to the lawyers, to the media or to anyone else they want to. Whether what happened in that hotel room was totally innocent or disgustingly guilty, it was not private. It was a state employee summoned by a governor. It was certainly not private if he used a state trooper to bring her there.