Five. They have enough story twists for 50 installments, or so they claim.
However, they also claim season one will not end on cliffhanger or Lost-like "WTF" moment, and to be honest, as I said before - for it to work - for everything in at least three timelines to resolve and tie together and for the viewer to put the two and two together and go "aha - I get it now" - two episodes is just not enough time. It would have to be a ground breaking, super innovative visual "closure moment" like we've never seen before, and I just don't see it happening.
It's kind of weird - on hand there moments of brilliance in this show like "what door" moment which is visually clever and settle enough for me to believe that they are capable of this glorious wrap up of epic proportions, but then I watch next episode and see obvious linearity errors in scenes, like basic level if-you-proof-watched-what-you-made-you-would-see-it-straight-away type of things - Bernards ever disappearing and re-appearing glasses between in-front and from-behind-his-ear camera angles in some scenes or like when Elsie finds the transmitter, talks on the phone and someone grabs her from behind. Cut. She's on stage, cut, she's on the main floor under the stage, cut, she's on stage again. Basic QC errors, really? And these guys are to go super-Memento on three time lines in final episode?
And those moments I think they either going to leave us high and dry in "are they, aren't they" suspense without answers until spring of 2018 (yup, not fall 2017) or they will crash and burn it into really unsatisfactory "you will need to read fan fiction about it" failed "tada!" moment.