Internet/marketing slang.
粉 'fans' < transliterated from English 'fans' (
粉丝 fěnsī = fans, the noodle pun).
吸 'suck/draw in' is what magnets do, so
吸粉 literally pictures pulling in fans. Sister terms:
涨粉 zhǎngfěn 'follower count grows,'
掉粉 diàofěn 'lose followers,'
变现 biànxiàn 'monetize.'