It was always 17 but people on the internet used the 14 and, of course, the 14 stuck due to it being the younger and more "newsworthy and controversial" age. If this affair happened, it would've happened circa end of '93/'94 which would make Steph around 17ish as Steph was born in September of '76. Savage and Liz split in early to mid 92 and were officially divorced by September or so, if I recall correctly.
Now do I believe it to be true...it likely is true due to the following:
1. People can talk about and say whatever they want about how close Vince was to Macho Man but they weren't really as close as Diesel/Hall noted and people have been closer to Vince including Shawn Michaels. One thing to note, when Savage left, Vince knew about it and gave Savage a public, on-air farewell and blessing so that leads to the assumption that Vince found something out AFTER Savage left.
2. An old friend of mine that some of you like, dislike, and possibly even hate (although hate is such a strong word and should not be used casually) has discussed this with me personally through the phone and I still have email correspondence as well; I have had numerous conversations with Dave in the past as we were very good friends at one point, especially when I was a true fanatic and not the mere casual fan, and emails and I have asked Dave this over the phone and through one email. Dave has said to me flat out that he has heard this from industry insiders and wrestlers, not just from the internet community. He first heard about this in `96, right before the NWO formed and he dismissed it but as the years went by, he started believing it was true because of the WWE's unwillingness to even mention Savage's name. When WWE execs were released/fired/quit, when Dave asked about Savage, all they would say is that they were not allowed to use his name in any storyline nor was he to be mentioned in the back, let alone on air. A few commented to Dave that they believed the rumors to be true. As Dave said, and I concur in a conversation in '08, Savage is the only one in the demonized, forbidden Benoit space; he's never acknowledged and it was like he never existed even though Savage was one of the top 2 or 3 stars during the WM boom period.
3. Mentioned above, Savage was Benoit'ed before Benoit; he was relegated to the WWE's Hall of Shame where thou name shall not be mentioned EVER. When has that ever happened before? Vince has brought back the likes of Sable (sued the WWE and won a shitload of money), Eric Bischoff, Paul Heyman, Hulk Hogan, and numerous others who have really fuckked him over so what did Savage do that was worse than what the likes of Heyman, Bischoff, and Hogan did?
4. To the point of #4, it wasn't until after Savage died that he was finally acknowledged. When the WWE released the first Macho Man DVD, which was LONG over due, it was almost touched on. Lanny beat around the bush, likely due to WWE's involvement, obviously, and if I recall correctly, Dusty Rhodes says something to the effect of "Obvioiusly we don't know the whole story and we will never know the whole story." when it came to why Savage was basically blackballed from the WWE for so long.
Again, could it be false and just a rumor? Of course it could very well be a rumor but all things point to it being true. I believe the Montreal Screwjob to be a shoot but between this Savage/Stehp rumor and the Screwjob, I think it's more likely that the Montreal Screwjob was a work than this rumor being false.