Answer :
In the given excerpt from Leo Tolstoy’s The Death of Ivan Ilyich, we can conclude the following about Gerasim from the phrase "the even white teeth of a healthy peasant" :
Gerasim is able to stay cheerful even in difficult times.
It is described in the excerpt that Gerasim belongs to the peasant class and peasants are not very particular about their dental hygiene. Gerasim is a peasant and does not belong to the bourgeoisie (the middle class which owns the means of production). He belongs to the working class and that is already mentioned in the excerpt.