Based on number from the US Census Bureau, the median household income of white people increased by 2.6% from 2016 to 2017, while that of black people "did not see a statistically significant change" (-0.2%; see the bureau report).
In the 4 previous years, black median income has been on the rise (after it declined in the 2007/2008 recession).
What is true is that the black unemployment rate continued the downwards trend it started in 2011 (but giving Trump - or any president - credit for this is "a stretch").
I am not aware of any numbers for 2018 (the census bureau will release those in 2019), but looking at the general trend, the numbers might improve further. I am not aware of any programs from the Trump administration which were specifically meant to increase black median income or help black poverty. The tax cut for example helps white people more than black people (mostly - but not only - because it helps high-income people more).