Can Jhin Legend ability play more than 12 runes with his passive?

No, you cannot exceed the limit of 12 runes on the board.

According to RiftJudge FAQ #5452, 12 runes is the maximum you can have on the board. If you are already at the maximum of 12 runes, the instruction to "channel 4 runes" from the ability of Virtuoso cannot be executed, and the effect simply fails to channel those runes.

Additionally, as established by RiftJudge FAQ #2680 (and Rule 430.1), "channeling" specifically refers to placing new runes from your deck onto the board; it is not equivalent to readying runes that are already there.