If I pay off a maxed out balance that's been maxed out for a few months totally, will I see my credit score increase significantly?

No, it will take a few months, before it changes at all. When it does, it will not make a significant change. If you pay off all and you have more than 8 accounts, (like you mention) along with several major accounts will make a difference. If you don't have any recent credit inquiries, or recent new accounts that have been opened for less than 6 months, it will also help. The biggest things are to have a lot of available credit, old accounts, - several years, no late payments for several years, and a boost in income in the past 6 months.

Remember, credit is built slowly, but can be ruined quickly. The trust (score) changes slowly, as things improve, over time. It cannot be repaired by any one event overnight. Just like in any relationship, harm comes quickly, but requires steady reassurements to rebuild it, or to initially build it to a respectable level.

Yes it will go up, but if you are expecting it to go up the day after you pay it off you will be disappointed. It will take several weeks

Ring them and ask them.

!!! Merry Christmas !!!