If the player is confused he might not realize he has options or be too intimidated at this point to ask questions at risk of feeling "stupid" being 16 sessions in and not having a grasp on the rules. Some players need a little more friendly coaching in the beginning before it clicks for them.
Throw the player a bone and offer him some choices. For example, "If you cast from there you will provoke a free hit, but if you wanted to you could try to carefully retreat and cast safely next round, take a step back or etc, etc."
I'm with IronWolf on this. It's very possible, that he's not asking for any advice not
despite the fact that he doesn't know - but
because he doesn't, and feels that he should already.
Long time aside, he's at newbie level - so treat him like a newbie. If there's a question with game mechanics, not tactics - help him out. For example, correct him: "yes, there actually
is a spell like that!", but don't say "you should cast detect magic on that rod-like stick before throwing it away, mate". After 2 or 3 AoO, say something like "if you cast spells that close to him, he will do that every round, you know" but not "oh get on that ladder and cast mage armour already!"
My attitude and gameplay is often reactionary to what I can do with group. If I see that the group is used to railroading, I start with railroad adventures with illusion of choice - and work my way up. On the other hand, when I was grouped with players who
really preferred rules light (as in total detest to pretty much any mechanics, "roll" being naughty word even during combat), I tried to slowly introduce various checks (but that example is not perfect, they really
preferred low-mechanics RP, so I ceded as GM).
So in this case I'd aim for no technical aid whatsoever (as it's big part of
ability to play a wizard), but start off giving all help necessary (though to a limit).
Note, that I presume that all he had until now was what he learned himself + some small info beforehand, not in-game help. If you tried it already for enough time, skip above, and go directly to paragraph below.
And if he still fails to learn anything - well not every class is for everyone! I have trouble playing wizards as well - a
lot, actually. So my caster of choice is sorcerer, or some character who's casting is only secondary. I suspect that you don't have
two wizards, so his lack of abilities hurts not only him - but fellow adventurers as well. Maybe he should just switch classes? I'd trade a bad wizard for competent bard in no time.