Q. Does G-d allow his followers to get blood transfusions/transfers?
(An additional question asked). If you have an opportunity to receive a transfusion should you choose from a fellow Jew?

A. Halacha permits receiving blood and encourages donation and help to others.
Chelkas Yaakov (2: 40), Igros Hakodesh (10 p. 239), Bedomaich Chayi (p. 62), and others permit receiving a blood transfer from someone that does not eat kosher, since in principle the impurity caused to the soul when consuming non-kosher food applies only to food eaten. (See Shaarei Horoah Y.D. p. 148 and others on midas chasidus). See also question 1617 in regards to organ donations.
Horav Shlomo Miller’s Shlit’a opinion is similar.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a