Can evince pdf reader be setup to do larger zoom than 400%?

It seems an optimization in the use of memory. If the page cache size is increased, evince will allow larger zoom levels.

This can be done from the terminal, allowing to zoom up to around 2700%, with:

gsettings set org.gnome.Evince page-cache-size 2014

"The maximal zoom is constrained by page cache size".

So the maximum zoom level depends both of your page cache and the PDF itself (the heavier, the less zoom capability).
For info, display page cache size (50 by default) with

gsettings get org.gnome.Evince page-cache-size

Set it to a bigger value to be able to zoom more, for instance:

gsettings set org.gnome.Evince page-cache-size 2000