How much do you reckon 4758 minerals/hr could cover in upkeep with someone who is rank 366? And is the last mineral jump in the 400's or 300's?

Personally, I had about 8k at rank 500-ish... But my upkeep was also low. I think you could raise yours to 6k at least. Now, at rank 540, I have 12k... Mainly because my upkeep has doubled... This gives me some extra credits. Also, once you run out of stuff to research (important stuff, that is), you can start selling research in the contract, which can help pay upkeep and also create a nice stash of credits.

Yes, but that still doesn't answer my questions.

Can someone please answer my questions?

Oh, right. I'd say you can easily cover like 3B upkeep, maybe 5B as well.

I do not believe there are any jumps in minerals after you start receiving Aidonium in shipments. All claims I've seen otherwise have turned out to be either based on a feeling and not recorded data, or people that unlocked the Dark Aperture Key and didn't calculate in the increase in credits/mp from that.

Sell an hours production to find out what you make per hour then multiply by 24
How often do you invade and what's your invade cost?
How often are you repairing in a day?
Do you need to pay part of your bases upkeep?

It's not very helpful to get an opinion from us since we don't know your daily/weekly expenses.
Your play style means everything in this situation and if you can answer the questions I asked, you will know how much upkeep you can handle.

I prefer 5 hours worth to get a more steady amount and less affected by the luck of a simple pull.

Anyway, we would need to know a bit more info to give better advice(well, other ppl would, I'm no expert on mining). The questions are more or less in order of relevance.
1. what is your Upkeep/day?
2. are you a builder? if so, any plan to change anytime soon?
3. would you by any chance be doing RP contract? your lv would be low for that but.... never know if u r a slow ranker who have it done.
4. Do you plan on changing/adding any module anytime soon? If so, which ones?
5. how many planet do you currently own? do you plan on getting more planet anytime soon? (this is the only large volume expenditure, if you plan on capturing a lot, you need a higher net income to store up the fee)
6. What is your current CR reserve? (this is tied to #4, if you already have a healthy reserve you won't need a large net gain even if u plan to go on capture spree)
7. what is your current shield/planet structure research? This affects your cost on planet capture as higher tech=better building=higher cost to construct. At your rank, the construct cost can still be significant(compared to colonize/invade cost. when you get to 800+ rank 200+ planet htou, this is negligible)
7. Any plan on buying any artifact/planet with KU(probably need to convert to CTP first, but that'd be an expenditure)?

Someone mentioned somewhere on the forum - nice specifics there - that each 1k MP roughly equates to 1 billion credits.
Seems to be pretty close to that for me. As mentioned by many of the wiser posters, we'd need to know more to judge whether that is enough for you...

For a comparison at a similar level, I'm Rank 352 and pull in 5346 units / hour with an upkeep of 1.5B (no I'm not a builder). The following info is all just anecdotal, so not 100% accurate.
I am able to handle this upkeep with no problems. I also have a MSB, so I am constantly repairing broken mods, I would estimate at least 6-7B a week, more when I have to repair my relays. I also donate 2-3B to the base a week. It is also no problem for me to save up some credits when needed, I like to keep close to 30B.
Based on that, I reckon I could easily cover 3B and probably even 4.5 - 5B, but I'd have to stop swapping mods.

You're in about the same boat as me then. I'm just shy of 8k MP/h with 3B upkeep and I do minor module switching on a daily basis, mostly the relays and energy and NPC modules.