Gelato Auto day 35 still veg, why?

There is some volatility in autoflowers -- e.g. an "XL" version came from somewhere, maybe your plant is one of those genetic lotery winners without being selected for the trait. Another possibility is that it is actually a photoperiod plant. If you see absolutely no hint of flowering, this may be the case. If set up to handle it, go ahead and give it 12hours darkness for a couple weeks... if not, give it another week or 2 and see what happens... if still vege it's getting way more likely to be a photoperiod. Can prune it back if doubling in size from that point is a problem. lol, make sure to prune it back if it is a photo, because you got another ~9 weeks from 12-12.