The Corleone Family is shown as of 1945 to have only two Capos - thus, only two crews.

After Vito's death the Family has three Capos - Pete/Frankie, Rocco, and Neri. How many guys do you think work as soldiers for the Corleone Family? How many made guys would you say there were in the Family at any given point? How many associates?

In GF, when Michael returns to the Mall after McCluskey broke his jaw, Sonny says "...a hundred button men on the street..." looking for Solozzo. That had to have been only part of the Corleones' total strength.
In II, Michael supposedly is "legitimate." But, at the Senate hearing, you see an FBI chart showing a substantial number of men, called "Buttons - Soldiers," under the Caporegimes. (See p. 218 of Harlan Lebo's "The Godfather Legacy" for details.)

There are a bounty of insufficiencies in the novel and movie that are grist for our posting mill. The size of the Corleone family is one of them. We read and see the family with, principally, only two capos. Sonny has a regime, but after his death his regime personnel are distributed among Tessio's and Clemenza's regimes. So, we're back to two. That seems improbable. If, as Sonny states, the Corleone family can match the other families gun for gun, then he's talking about 1,000 men (I don't buy one Board members's argument that those 1,000 guns would include associates recruited just for that purpose). If the Corleone strength is that great, then only two capos would be an administrative nightmare for Tessio and Clemenza.

It does seem like Clemenza and Tessio would be something more along the lines of underbosses, with capos reporting to them. Of course, that gets undermined by Clemenza dealing directly with Paulie and Rocco.

Yeah, two Capos with 500 guys each would mean they'd have literally no fuckin free time.
I get the sense that Tessio and Clemenza were given very long leashes even before Vito retired. Think of it like the Holy Roman Empire in a sense. Whatever Vito said was LAW. Vito says no drugs - no drugs. Vito says Carlo or someone can't join the family - they're out. Vito wants someone dead - they're dead. But...Tessio and Clemenza could do what they wanted outside of that rubric and as long as they're kicking up money. So basically you might have guys like Frankie basically being the equivalent of a Capo with a crew of guys reporting to Clemenza, but having the official rank of Soldier.

Also, Fredo is said to have his own people in GF II. Which makes that three official "crews".

I think the Godfather family was divided something like:

BOSS

Underboss (a floating position that depended mainly on who was more influential at the moment - Sonny was basically acting Underboss before Vito was shot it seems)

Consigliere

Capos (Sonny, Tessio, Clemenza, Fredo; later Rocco, Al and Frankie)

Sub Capos (Frankie, Al Neri; later Willie Cicci)

Soldiers/Buttons (Willie Cicci, Al, Rocco, etc)

Associates (anyone who owed the Don a favor/Judges/Politicians/hired thugs)

Basically a massive layer of insulation between THE DON, and the lowest level guys. I mean, Willie Cicci alludes to never having really interacted with Michael as a Button, and yet he was a made guy, a soldier. As Willie put it "The family had a lotta buffas"

Kinda reminds me of the Chicago Outfit's structure in a way

The Boss
Underboss
Street Bosses i.e Clemenza and Tessio
Soldiers with their own crew's of Associates

So the Corleone's might've had 20/30 Soldiers reporting to Sonny, Tessio and Clemenza with Associates reporting to them

Yeah, Clemenza and Tessio were basically street bosses in charge of sub-families with their own hierarchy. The Corleone family is the equivalent of the Genovese family so they're supposed to have hundreds of soldiers and even more associates. 1000 "guns" in manpower seems to be in the right ballpark.

That's how I picture it. It's like the Roman Empire. Vito was the Emperor, with two regional Governors basically under him who had their own governors (who in turn commanded small armies of made guys and associates) all reporting back to Vito. Notice that in GF 1, only Clemenza and Tessio are around Vito in a business capacity. He used them as insulation from the Feds effectively. And then Michael used Tom in a similar way in II.

I like to think of the Tessio wing being more aligned with things like gambling, the unions and such while the Clemenza wing were the shooters, prostitution guys and such.