from what i have read about him and in his autobiography, tesla did not seem to doubt himself. i have the impression of a man of amazing optimism.
Only an INTJ can have that much originality and confidence in his visions. Would an entp never marry and die alone? Maybe the rumors were true, he's not a man, we can't define him in humanistic terms. Mark Twain made a story which referred to Tesla as an angel, they were good friends.
I don't think he was an intp either, because he poked holes in Einstien's theories of relativity.
Concerning Albert Einstein's relativity theory, Tesla stated that '...the relativity theory, by the way, is much older than its present proponents. It was advanced over 200 years ago by my illustrious countryman Boskovic, the great philospher, who, not withstanding other and multifold obligations, wrote a thousand volumes of excellent literature on a vast variety of subjects. Boskovic dealt with relativity, including the so-called time-space continuum...', (1936 unpublished interview, quoted in Anderson, L, ed. Nikola Tesla: Lecture Before the New York Academy of Sciences: The Streams of Lenard and Roentgen and Novel Apparatus for Their Production, April 6, 1897, reconstructed 1994).
Tesla was critical of Einstein's (theory of) relativity work,
...[a] magnificent mathematical garb which fascinates, dazzles and makes people blind to the underlying errors. The theory is like a beggar clothed in purple whom ignorant people take for a king...., its exponents are brilliant men but they are metaphysicists rather than scientists... (New York Times, July 11, 1935, p23, c.8).
Tesla also stated that:
"I hold that space cannot be curved, for the simple reason that it can have no properties. It might as well be said that God has properties. He has not, but only attributes and these are of our own making. Of properties we can only speak when dealing with matter filling the space. To say that in the presence of large bodies space becomes curved is equivalent to stating that something can act upon nothing. I, for one, refuse to subscribe to such a view." (New York Hearald Tribune, September 11, 1932)
I think this is INTJish, he's saying that it's a great theory, but most likely it doesn't work in reality.
Math itself is not as logical as you think, if you calculate the circumference of a circle using the formula (Pi x r^2) Pi is an irrational never ending number, so in theory, the answer you get using this equation ALWAYS says the circle doesn't complete itself and never will. But in reality we all know this isn't true, a circle can and does meet it's other end.
In this sense I can easily relate to what Tesla meant by when he said mathematical mumble jumble.