How many humans a day would T-Rex need to eat to get its needed calorie intake?

Let’s start with some assumptions first. Since T-Rex lived mostly in North America and Europe, the question changes to “How many average Europeans could a hungry T-Rex eat?”

Let's take an average European person's weight as 80.7kg.

Appetite of a hungry T-Rex: For this statistic, we view all of these humans as being a one-time meal with enough meat to feed a T-Rex for a week, or 7 days. Given that a T-Rex could be expected to need to eat 4–7% of its own bodyweight in meat per day, just like its closest modern ecological analogue, the Bengal Tiger.

Our selected T-Rex has an estimated mass of 9000kg, and truly hungry being missing out on 7% of daily intake every day, for a week.

So, 0.07*9000= 630kg*7 days = 4410kg.

In order to reach 4410 kg, our extremely starved T-Rex would eat 54.6 average Europeans, before satisfying its appetite.

Thus to finalize it, a large, very hungry T-Rex could eat up to 55 people at a time, to satisfy its hunger.

The city of Moscow had a population of 15 million people in 2021. One T-Rex needs slightly more than 2860 humans a year. So Moscow alone could feed a big population of T-Rexes for several years.

By the way, the average life time of T-Rex is estimated being just about 30 years. And T-Rex's walking speed was roughly between 7.2 and 10.8 km/h, about as fast as a mediocre human runner.