The boxoffice prediction game is really tough with scifi films because the scifi nature of a film is hardly the reason most people would watch the film, so it's really about what other factors there are which could draw them in or repel them.
Arrival is less than two hours long, is presented as a family relationship drama mixed with first contact with aliens. I think it's fairly relatable and not something that turns people off if they're curious about it or the word of mouth is good.
Blade Runner is almost 3 hours long, is almost certainly going to be more of a thriller of sorts which attracts more of a male skewed demographic but also more cerebral and atmospheric which might be more challenging than some of those audiences would like. It's also 3 hours long. I would say the closest comparison here is Nolan's Interstellar, except without having "From the director of the Batman trilogy" pasted on it.
Another factor to consider: How much international pull does this need to be successful? Arrival was basically 50/50 with 100 million domestic and 100 million foreign. For a good level of success a blockbuster that costs >150 million is going to need much more foreign success to carry it unless we're expecting a HUGE domestic take, which looks unlikely.