It is actually Лёв [yo] with ё, so it should be Лёв Толстой. The writer himself pronounced his name as [lyov] with ё according to old-Moscow pronunciation. His family and friends also called him Лёв [lyov].
It can be very confusing for a person studying the Russian language to know when to read Ё [yo] and when Е [e].
Take, for example, surnames.
In a lot of foreign names translated into the Russian language the sound Ё [yo] disappears and becomes E [e]:
e.g, Churchill – there is a sound [yo], one can definitely hear it, but in Russian it is
Черчилль [chErch-ee-l’] – no Ё [yo] whatsoever.
And in other names, it is written E but everybody says Ё [yo].
Who in his right mind will even think to say [gᴧrbᴧchEv] instead of [gᴧrbᴧchyOv], though you will never find a printed text where the name of the first and the last President of the Soviet Union is spelt with Ё [yo] as Горбачёв.
So what is it about letter Ё? Why does it appear in some words and completely ignored in other?
Letter Ё as “a national idea”.
In modern Russia letter Ё [yo] has become “a national symbol” and even has its own monument in Ulyanovsk.
The argument about the letter Ё [yo] has been going on for a while. It has evolved in one of those arguments which are on the border between linguistics and politics, like a dispute about the preposition in the expression “in Ukraine”: is it на Украине or в Украине?
Some linguists argue that the letter Ё should be used everywhere where it is pronounced: if we hear Ё [yo] we write it down and not E instead of it. The others say that there is no need to do that because nobody will ever think to say Елка [yElkᴧ] (a fir tree) instead of Ёлка [yOlkᴧ], even if it is spelt with E in the text.
Some people think that there is no place for the letter Ё in the alphabet because it is just a symbol artificially created 200 years ago to replace the sound [yo] and the Russian language can comfortably exist without it.
Princess Dashkova – a godmother of the letter Ё [yo].
The 7th letter of the alphabet appeared in the Russian language only at the end of the 18th century.
It is believed that the Princess Dashkova at one of the meetings of the Russian Academy of Sciences wondered why in the word Ёлка [yOlkᴧ] (a fir tree) which in those days was spelt as “ioлкa” there are two letters <io> to symbolize one sound [yo]. And she suggested using the letter Ё instead of writing everywhere two letters <io> to indicate the sound [yo].
And of course, it would not be the history of Russia including the history of linguistics without... Stalin.
The story says, though nobody knows if it is true or not, that Stalin was about to sign a decree in which the surnames of a few generals were typed with E instead of Ё. According to the story he got absolutely furious and the next day the decree was issued ordering to use the letter Ё in all printed and written texts.
So what are the rules?
Shall we write the letter Ё ё every time and everywhere we hear it? And is it a mistake not to write it?
The rules are quite simple. But the first thing to remember when you study Russian that if there is ё in the word – it is always stressed.
As to the writing, the letter Ё should be written in
1) the texts for kids and foreign students, or in any other texts which have the words with the stressed vowels marked, including all dictionaries;
2) in cases when using letter E instead of Ё might lead to misunderstanding, e.g., the word все [vse] means “everybody” while the word всё [vsyo] with ё has a completely different meaning, it means “everything”;
3) when it is necessary to draw attention to the pronunciation of uncommon “exotic” words ,e.g., река Олёкма – river Olyokma.