The best stats is when a student comes back or buys a lot of lessons. Most students try a lot of teachers before buying a package. I know that because the teachers that the student tried will show on their profiles , unless they made it private.
Trying out a lot of teachers is a normal behavior of learners for them to check who is suitable for them.
There are many choices here on Italki so when the lesson and student ratio is the same or is close, it only means one thing, the teacher is pretty bad.
A teacher can teach at least 5000 lessons and they have the same number of students, it means that the quality is not good.
@Phil is right . There are teachers with 5 stars rating but when you watch their video or look at the lesson and student ratio, they fail to keep regulars. Attracting students is easier than keeping regulars, especially that there are hundreds or thousands to choose from.
The video will show a glimpse of the teacher's teaching style and personality.
The student comments will show some positive outcomes from learners.
It will also show the teaching style at least.
The students will use good adjectives to describe the teacher. Is the teacher cheerful? Is the teacher disciplined? Is the teacher punctual?
Different learners have different needs. A teacher will usually mention their specialization. A teacher who is great with kids, does not necessarily mean that they are great with adults or exam preparation.