what indicators does Orwell include that the gap between rich and poor is widening in the final chapters? Are these indicators realistic in our world?

I think the best explanation for this question can be found in gradesaver's Chapter 10 analysis. The direct link is provided below.

http://www.gradesaver.com/animal-farm/study-guide/section10/

As for the second part of your question, Animal Farm is as relevant today as it was when written. Think about current events around the world and how they apply to this theme, and you'll have your answer. You teacher wants your opinion....... this is a question intended to make you think.