PoE is an F2P online action RPG which falls into a more casual gameplay/genre, Eve Online is a full fledged P2P sandbox MMORPG that's still active, with a huge subscription count and a fairly good exchange rates to RL cash. I'll let this two facts slide for now and not going to be put into account on what I'm about to say below.
A level 81 witch, not to mention a summoner, should take two or at most three weeks to level if you're very slow. Your offer for 5 billion isk in Eve is the equivalent of around 8-10 months of gametime roughly (depending on the current rate of PLEX), or the equivalent of a 4-5 mil SP character depending on remaps and spec. So no, there are no scenario, not even when your level 81 witch includes a 6L offcolor shavronnes, andvarius, even added to that a soultaker or a 6L voltaxic bow or something else, can even came close to 5 billion isk worth of Eve Online equivalent. The only exception is that if you include a few stacks of exalted orbs and a few kalindras, which I doubt it.
At best, your character, assuming you're geared up for summoner, would go for a few hundred mil of isk, and that's pushing it. Sorry mate.
