This is the 1st thing I asked about when I got in the yellow track pack car. I sat & blipped the throttle many times (Ryan teased me afterwards in fact for sitting there for 5 mins revving the car, lol) to compare to my Gen4. He explained that the delay has been halved from around 450ms to 250ms, and that with all the electronics and safety stuff they have to deal with there's no way to get it to be zero, but they made a concerted effort to improve this and they did. IMO on a gen4 the delay isn't that big of an issue, I know some guys talk like it's undriveable, I found that I complained a bit at first and then after just a bit of time in my gen4 that I didn't even think of it. In the gen5 I'm certain this "delay" is no issue. It felt great to me, everything about it, shifter is like an MGW equiped car, it had a real "tight" sense to the whole car and the throttle is part of that. So, if by fixed we mean a non-issue, than IMO it's defintiely fixed. If by fixed we mean zero delay, then no, there is a 250ms delay that my engineer with me said is the minimum they could achieve .. and IMO again, is a non-issue.
Hope that helps.