Count: 0 — No genuine English pronouns begin with the letter J. In the Complete A–Z List of Pronouns this page returns no entries that meet the criteria, even though the letter J is common elsewhere in English; note that the palatal sound /j/ appears in pronouns like you, but those words start with the letter Y in standard spelling rather than J.
Understand that the absence reflects historical and structural facts about English. Pronouns form a very small, closed word class that preserves ancient roots from Old English and Proto‑Germanic, and those roots rarely began with the sound or letter that became J. The letter J itself is a relatively late graphic development (originally a variant of I), so it did not create new native pronouns during the language’s development.
Consider items that come close but do not qualify. No standard personal, possessive, reflexive, demonstrative, relative, interrogative, indefinite, reciprocal, or distributive pronoun in modern English starts with J; some dialectal, archaic, or non‑English self‑reference words (for example, pronouns from other languages) begin with J, and some English pronouns begin with the J sound but are spelled with Y (you, your). Check nearby alphabet pages such as Y for many of the common pronouns readers expect.