The 5dIV is 30MP. At a 1.6 crop, it is 11.7 MP. The 7dii is 20MP. So, you'd lose about 41% of the pixels, but the 5dIV will have better pixels :). For equivalent MP, you'd be around a 1.2x crop from full frame.
Do you crop your 7d much? If you only do minor crops on the 7d, the 5d is...