The extraordinary ability ranged weapon bond of the magus archetype eldritch archer says, "Holding her bonded item does not prevent the eldritch archer from providing somatic components for her spells."
But on Choosing a Spell says, "To cast a spell, you must be able to… manipulate the material components or focus (if any)" necessary for casting the spell. Unless the GM can be convinced that the PC can manipulate the material or focus components with his mouth, the PC'll likely need an empty hand to manipulate any of the spell's material or focus components.
Thus, as written, an eldritch archer magus must still manipulate material and focus components, probably using an empty hand. (Also note that I've never heard of a GM that didn't allow a spell's somatic components, material components, and focus components to all be used with the same at-first-empty hand, but I've also not heard of a GM who allows a caster to manipulate material and focus components with his mouth.)
In sum, this means the typical eldritch archer magus must pick his spells carefully—that is, spells without material and focus components—if he's to cast spells while wielding a two-handed ranged weapon. However, it's a free action to take a hand off a two-handed weapon and a free action to put a hand back on a two-handed weapon (see here), so that's an option instead (although that's usually not an option if casting off turn a spell that possesses a casting time of 1 immediate action).
The feats Eschew Materials or False Focus (perhaps by wearing armor or employing a bow created with the feat Create Reliquary Arms and Shields) will certainly be useful if manipulating material components has become an issue for the eldritch archer magus.