Jupiter promotes for expansion and is a drive for learning. This is different from Mercury which is the "act" of learning and analysis itself. Jupiter's home sign is Sagittarius as this fire sign promotes for the drive to explore and journey; the opposite sign of Gemini is detrimental to Jupiter, as Gemini is quick and short, like a nervous twitch. Both apply to learning, but in different ways.
Jupiter in Gemini could promote for someone to learn about reading and writing, such as across their collegiate career, whereas doing the ongoing Mercury in Virgo square would directly make someone a better reader or writer.