I'm pretty positive at the very least that Brujah, Toreador, Ventrue and Malkavian's are all playable. Outside of their pin symbol inclusion, Brujah is 100% confirmed by the developers in interviews, Ventrue is almost basically confirmed by the one high-rise office location in the clans section of the official website as that just screams it's them (plus of course they'd be in Seattle lore-wise as vampires have run Seattle for a while), Toreador's I think definitely won't be cut since they've talked a lot about sexiness being a big part of the game, and that class is all about being sexy. Malkavian's I think are in because they were the fan favorite class in the original game, they mention they've thought of things fans would want in a sequel, and there's no way they don't know Malkavian's are loved, especially with things like the stop sign being included with versions of the game.
I think really the only two mysteries are the last clan and the "Bonus", for whatever that means. I do think you're right that Tzimisce is the fifth and final regular clan (unless Malkavian's are the Bonus?), but that does lead one more. Going by the pins, both Independent and Giovonni are listed. The "Bonus" could be Independent, as the Bonus does have a pretty normal looking apartment and it'd be a "bonus" since it's a pathway that's not technically a clan.
So my current theory with all of this info is the playable Clans are:
-Brujah
-Toreador
-Ventrue
-Malkavian
-Tzimisce
-Independent (Clan-less)
Just my current theory with the pieces.
This logic makes a lot of sense. The only question I have, as someone who was more mired in Mage than Vampire, isn't your clan determined by who sires you, like kind of a biological thing almost as much as a social thing? Is it really possible to be a clanless vampire? I'm not sure how the whole siring/ascension process works for vampires.