If you want a Model Y immediately you will have to pay a lot more than a $15k premium. The earliest official delivery date for one is April 2023, and that's just for the premium models.
It would greatly depend on your driving habits. I’m averaging 2k miles a month. My electricity cost averages around 4 cents/mile(14c/kWh). At my current gas prices($5.75) I’d need to get 142mpg to get 4 cents/mile. The rav4 is complicated because it’s both, but I’d get about 40% of my day on electric and 60% on gas. That means 4c/mile for the EV(even granting it’s as efficient as the Tesla which epa numbers aren’t as good) and 36mpg(epa Highway rav4 prime) on the Highway for 60% of my day. 36mpg would be about 16c/mile. So in an average day about 100 miles, it’d be 40 * .04 + 60 * .16 = 13.5c/mile averages over a day. So 24000miles/yr multiples by .04 or 0.135 and it’s $960 vs $3240. That points to in excess of $20k in savings over 10 years. If someone goes 40 miles or less a day these numbers favor a prime quite a bit more.