I'm going with Valarian on the texture: I don't think it's too much. At least, not by much.
The fonts, though: they've got to be more legible. You might want to consider cleaning off the texture from where the fonts go, to help legibility, but you probably ought to consider changing the font up entirely to a legible one, even the larger fonts. For instance, this map was made in "Circa 3059 ??". I can identify Circa and the numbers well enough, but the last two letters are completely opaque to me.
I'm not sure that the forking rivers are quite a problem - normally they are, of course, completely unrealistic, but at this scale (with that 30 Mile marker) the forks appear to occur roughly 10 miles inland. This is within the range for a river delta type formation. However, if they are intended to be deltas, that's not entirely clear from context. On the other hand, if they're just suppose to fork downstream... as mentioned it remains rare (though maybe not entirely impossible) that a river splits and forks in the downstream flow.
Anyway... good luck with the novel. It's the same thing that drew me here: having been working on a novel for the last decade+ (and gone through many iterations) my decision of about two years ago to reboot everything and start from scratch on that project necessitated (in my mind, anyway) a new map, and I wanted to go digital for the flexibility that offers.
Given that this is for your novel, the question, though, is: is this map for your own personal use (as mine is) to help illustrate to yourself while you write or intended to go with the novel or otherwise for public consumption (i.e. like on the novel's website or something)? If the former, then many of these factors don't matter, as the only relevant criterion is whether the map meets your personal needs. If the latter, then the legibility and everything become an actual concern.