He didn't. The quotes in these tweets are fake. If I search for these quotes these tweets are the only results. Twitter is a hostile platform to reality as reality can get in the way of virality. Hence why you never see sources on twitter. This was likely written by someone with only a passing familiarity with gandhi's position on WWII who probably guessed at how he would speak based on his character in Civ.

What did gandhi actually think the Britiish should do in 1940? In his actual words:

I want you to fight Nazism without arms, or, if I am to retain the military terminology, with non-violent arms. I would like you to lay down the arms you have, as being useless for saving you or humanity. You will invite Herr Hitler and Signor Mussolini to take what they want of the countries you call your possessions. Let them take possession of your beautiful island, with your many beautiful buildings. You will give all these, but neither your souls, nor your minds. If these gentlemen choose to occupy your homes, you will vacate them. If they do not give you free passage out, you will allow yourself, man, woman and child, to be slaughtered, but you will refuse to owe allegiance to them.

Basically he was speaking for an extreme form of non-violent civil disobedience, not capitulation.

Also a famous gandhi quote: "Stop believing everything you see on twitter you gullible rube"

It's important to remember: few outside of Germany knew that concentration camps existed, certainly not the scale of them or how appalling the conditions were. Consider the amount of information that Gandhi could reasonably have about activity in Germany and Europe. As far as he was concerned, the evil empire dominating his country was just having a costly spat with the evil empire dominating another country, sacrificing the welfare of his people for those of their neighbours in Europe.

I would like you to lay down the arms you have as being useless for saving you or humanity. You will invite Herr Hitler and Signor Mussolini to take what they want of the countries you call your possessions. Let them take possession of your beautiful island, with your many beautiful buildings. You will give all these but neither your souls, nor your minds. If these gentlemen choose to occupy your homes, you will vacate them. If they do not give you free passage out, you will allow yourself man, woman and child, to be slaughtered, but you will refuse to owe allegiance to them.

If one Jew or all the Jews were to accept the prescription here offered, he or they cannot be worse off than now. And suffering voluntarily undergone will bring them an inner strength and joy which no number of resolutions of sympathy passed in the world outside Germany can. Indeed, even if Britain, France and America were to declare hostilities against Germany, they can bring no inner joy, no inner strength. The calculated violence of Hitler may even result in a general massacre of the Jews by way of his first answer to the declaration of such hostilities. But if the Jewish mind could be prepared for voluntary suffering, even the massacre I have imagined could be turned into a day of thanksgiving and joy that Jehovah had wrought deliverance of the race even at the hands of the tyrant. For to the godfearing, death has no terror. It is a joyful sleep to be followed by a waking that would be all the more refreshing for the long sleep.

Religious fanatics rarely deserve the adulation their beliefs receive.

I mean, it feels like the tweet explained it well (I know nothing of the subject, but if the tweet is accurate I don't feel it needs any more explaining).

Ah yes, the pre-emptive starving several years before the war

The dude was a pedo, so who knows what really went on inside his noggin.