Which is correct

I am having a debate with a friend regarding the use of "They're" vs. "There" in the following sentence:

They're a lot of people who are praying for his recovery. versus There are a lot of people who are praying for his recovery.

If you need fuller context - Here's a back drop:

I hope I didn't disturb you when I reached you on your cell phone yesterday. It seemed like you were rushing to get Jim to the doctor's office. How awful to learn that he has this dreadful disease. Please know my heart goes out to you. If there is anything I can do to help you through the course of her treatments, please let me now. Also, having spoken to some other of her friends, I know my sentiments are echoed. They're a lot of people praying for his recovery.