Are there English equivalents to “Samurai uses (show off) a toothpick, even he hasn’t eaten anything (for a day)”?

In addition to the phrase suggested by Elian, I feel that keeping a stiff upper lip, is close to the meaning of the Japanese proverb you quote.

Someone who has a ​stiff ​upper ​lip does not show ​their ​feelings when they are ​upset (Cambridge Dictionary)

To be courageous or stoic in the face of adversity. (The Free Dictionary by Farlex)

A steady and determined attitude or manner in the face of trouble (Merriam-Webster)

One who has a stiff upper lip displays fortitude in the face of adversity, or exercises great self-restraint in the expression of emotion. (Wikipedia)

The Phrase Dictionary further expands on its meaning, saying

That 'do your duty and show no emotion' attitude was expressed in Alfred, Lord Tennyson's The Charge of the Light Brigade:

  Theirs not to make reply,
  Theirs not to reason why,
  Theirs but to do and die:
  Into the valley of Death
  Rode the six hundred.

Which makes me think the phrase may in some ways reflect the martial (?) philosophy of the samurai, although maybe not which as much weight on honour or wealth as the question implies the Japanese phrase has.

Related phrases suggested by the Phrases Dictionary, which have more to do with keeping a sunny disposition, are "keep your chin up" or "keep your pecker up".

Consider, put on a brave (or bold) face/brave front

To react to or face difficulties, setbacks, or adversity with high spirits or good cheer. Farlex Dictionary of Idioms

To behave in a way that makes people think you are happy when you are not Cambridge Dictionary