This is a good point Anne Benedetti — There’s something confusing or fluid about Ivanushka. In the English translation I have, they’ve used SHE (Louise and Aylmer Maude, the translators). Possibly they thought that Ivanushka had adopted male gender. One of the reasons for wanting to pass as a boy may be that this would be more compatible with the lifestyle of a wanderer. These people are not pilgrims in the sense of being on one particular journey — I think they have a permanently itinerant lifestyle.
Could this be a translator’s mistake, provoked by Andrei’s leg-pulling?
There seems to be some sort of sibling humour between Andrei and Marya — and another reading is that this is just fooling around. The name is definitely a boy’s name: the “ushka” ending is just a diminutive. Tolstoy actually does say “him” in the Russian “… лицо Иванушки, который, поняв, что речь шла о нем, хитрыми глазами оглядывал всех”. (my rough translation) “Pierre peered at Ivanushka’s face, who, realising that he was being discussed, looked round at everybody with cunning eyes”
But then why does Tolstoy tell us in the next paragraph that (he) looked around with “лукавыми женскими глазами” — “crafty woman’s eyes” without any pronouns?