I did a little research and this is what I found. Apparently, the quote may have been fabricated by Sydney Omarr in 1989, although it was inspired by Morgan's actual interest in astrology. We know this thanks to renowned high-profile-client astrologer Evangeline Adams's autobiography, The Bowl of Heaven, where she says the following:

I do know about the late J.P. Morgan’s belief in astrology, because – well, because I taught it to him. I read his horoscope many times, and furnished him during the last years of his life a regular service, explaining the changing position of the planets and their probable effect on politics, business, and the stock market.No further proof of his interest in the science is required beyond the fact that he renewed this service from year to year.

The first time he came to my studio, his attitude was frankly one of curiosity tinged with suspicion.I had a heavy Chinese screen in one corner of my studio, and I remember how Mr. Morgan pulled his huge frame out of his chair and looked curiously behind the screen before beginning the interview. But that attitude melted away at the first meeting. And, in his last years, he asked me from Egypt to join him and his party in the Orient, where he had gone on his famous yacht, the Corsair. His idea was to spend several months in a scientific investigation of the occult in those parts of the world where its practice reaches back into prehistoric time. I declined the invitation, not because I didn’t appreciate the opportunity, but because I preferred to pursue my own investigations. (p. 107-108).