Indeed, the gloss "otherwise" and also "if not" are two of the renderings in the standard BDAG lexicon (A GREEK-ENGLISH LEXICON of the NEW TESTAMENT and other EARLY CHRISTIAN LITERATURE) under the word ει.
Interestingly enough, if you look just 9 verses below in John 14:11, one sees the same ει δε μη translated as "or else" in the KJV, as also in Rev 2:5, 16. In Mark 2:21, 22 the KJV renders ει δε μη as "else" both times.
In 2 Cor 11:16 the KJV renders the ει δε μη γε as "if otherwise." Also in Matt 6:1, the same expression is rendered "otherwise," while in Matt 9:17 it is "else."
One interesting thing is that the KJV renders ει δε μη γε as "if otherwise" in Luke 5:36, but the exact same expression as "else" in the very next verse.
Surely DrJamesAch will concede that the rendering of the expression is entirely up to the translational preference of the translators, as the expression has various legitimate renderings in English.
