I'm not aware of any dogmatic statements of the eastern orthodox churches on the historicity of the Biblical texts. Which isn't dispositive, I may just be unaware, but I suspect one reason I haven't found any is because the sort of genre of "historicity", in the way we use it, is fairly modern. Orthodoxy doesn't consider the Bible as being primarily a book of history in the modern, academic sense, at the very least. Gregory of Nyssa writes about historia and allegoria as modes of interpretation, in his defense of his allegory of the Song of Songs, but what is meant by "historia" is a bit different from the modern meaning of "historical".
So I guess what I would say is that there is probably not some unifying general theory, as a matter of dogma. Individual texts are read in different modes, or even in more than one. Obviously orthodoxy considers the death and resurrection of Christ to have been (also) an historical event, although it should also be clear that it transcends history, in the same way that Orthodoxy considers the practice of the Liturgy to bring the events commemorated also into the present time, in a mystical and experiential way. In St. Symeon the New Theologian's Discourses, he writes about the resurrection in a mode that transcends a mere accounting of the historical:
"But if you will, let us look and carefully examine what is the mystery of that resurrection of Christ our God which takes place mystically in us at all times, if we are willing, and how Christ is buried in us as in a tomb and how he unites Himself to our souls and rises again, and raises us with Himself. Such is the aim of our discourse. Christ’s resurrection is thus our resurrection, ours who lie here below. Through His resurrection in us it comes into being in us, is shown to us, and is seen by us. Most men believe in the resurrection of Christ, but very few have a clear vision of it. Those who have no vision thereof cannot even adore Christ Jesus as the Holy One and as Lord. As it is written, “No one can say ‘Jesus is Lord,’ except by the Holy Spirit”.
That most sacred formula which is daily on our lips does not say, “Having believed in Christ’s resurrection,” but, “Having beheld Christ’s resurrection, let us worship the Holy One…” How then does the Holy Spirit urge us to say, “Having beheld Christ’s resurrection,” which we have not seen, as though we had seen it, when Christ has risen once for all a thousand years ago, and even then without anybody seeing it? Surely Holy Scripture does not wish us to lie? Far from it! Rather, it urges us to speak the truth, that the resurrection of Christ takes place in each of us who believes, and that not just once, but every hour, so to speak…"
Following Gregory of Nyssa, I would suggest the Orthodox key to interpretation is not so much in choosing the historical vs allegorical vs symbolic mode, as much as of finding spiritual profit that leads into the experience of Life in Christ, as a practical matter. Gregory writes:
"It seems right to some church leaders, however, to stand by the letter of the Holy Scriptures in all circumstances, and they do not agree that Scripture says anything for our profit by way of enigmas and below-the-surface meanings. For this reason I judge it necessary first of all to defend my practice against those who thus charge us.
In our earnest search for what is profitable in the inspired Scripture (c.f. 2 Tim 3:16) there is nothing to be found that is unsuitable. Therefore, if there is profit even in the text taken for just what it says, we have what is sought right before us. On the other hand, if something is stated in a concealed manner by way of enigmas and below-the-surface meanings, and so is void of profit in the plain sense, such passages we turn over in our minds, just as the Word teaches us in Proverbs, so that we may understand what is said either as a parable or as a dark saying or as a word of the wise or as an enigma (c.f. Prov 1:6).
One may wish to refer to the anagogical interpretation of such sayings as “tropology” or “allegory” or by some other name. We shall not quarrel about the name as long as a firm grasp is kept on thoughts that edify. (Homilies on the Song of Songs)