Most recent data I have for BYU is 2019-2020 academic year. That year they had $72M in athletics revenue, 26% of which came from ticket sales, meaning $18.7M in ticket sales
(see https://kslsports.com/437719/byu-revenue-expenses-athletics/)
Meanwhile Utah in that same season had $18.5M in ticket sales. (see https://utahutes.com/documents/2021/1/19//FY20_NCAA_Revenue_and_Expense_Report.pdf?id=23450)
That’s all sports, not just football, but I’d assume football makes up the majority of it. Given that BYU’s ticket sales were calculated as a percentage they could be anywhere from $18.2M (25.5% of $71.5M) to $19.2M (26.5% of $72.5M) and the unknown variable of non-football sales, I’d say that neither school has a major advantage over the other when it comes to ticket sales.