In 1912, he published his findings. But in 1915 Einstein published his GR Field Equations.
We already know the visible mass of Galaxies is much less than the real accountable mass of them based on Rotational Curves.
We know Gravity causes Red shift - from Stars in it and from Galaxy itself from its Black Hole and Surrounding Black Matter.
Has this been reconciled?
We assume Red Shift is happening from Flying Away Galaxies, away from Earth.
It's true that Slipher was the first to measure the recessional speed of galaxies, and even their rotational velocity; but although his 1912 paper was generally acknowledged by 1917, there was no obvious relationship between the recessional speeds and any other quantity. In fact, some galaxies (e.g., the Andromeda Galaxy) have a blueshift, rather than a redshift, indicating that they are moving toward us, rather than away. So there was no reason to suspect that the motions were anything other than random, and there was also no way to measure the distance of galaxies, so their sizes and masses could not be determined, either. It was only when Hubble used Cepheid variables to estimate the distances that the universal expansion was discovered by him and Humason, and that wasn't until 1929. So when Einstein published his paper on General Relativity, there was no reason for him to think that there was any net contraction or expansion of the Universe, as predicted by his theory. If Hubble and Humason had already shown that there was a general recession that depended on distance, Einstein would have concluded that there was no need for the fudge-factor "lambda" that he invented to keep his theory from predicting a contraction or expansion of the universe (he later claimed that was the biggest mistake of his career).
As far as the red shift caused by the mass of material inside galaxies, it is far too small to observe save for extremely dense objects, such as white dwarfs (for which it is barely observable), neutron stars and black holes. For any galaxy taken as a whole there is no significant redshift due to its gravity, because its mass is too spread out to give it the extremely high gravitiational force required to create a significant redshift.
Also, even if galaxies could produce significant redshifts, there is absolutely no reason to believe that more distant galaxies would have redshifts any different from nearby ones, so that could not explain the observed Hubble expansion.
In other words, save for a few objects scattered in various places inside galaxies, gravitational redshifts are insignificant, and in any event cannot explain the Hubble expansion. It must, therefore, represent a real expansion of the space between the galaxies, just as predicted by Einstein's theory. (Note: Although the cumulative rate of recession of extremely distant galaxies is very large, the expansion of space due to General Relativity is very small over distances that are small compared to 50 million light years, being only an increase of 70 km/sec in a space 3.26 million light years on a side. It's just that when you get a few tens of thousands of times as much space, the cumulative expansion becomes tens of thousands of times larger.)
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