The phrase "gain immensely" is correct and can be used in written English.
It is typically used to indicate a great increase or improvement in something. For example, "My understanding of the English language has gained immensely since I started taking classes."
All three dances gain immensely by being seen together.
If Tsipras's pseudo-leftist government doesn't do what it promised, Golden Dawn will gain immensely.
It's not just individuals who benefit from one-on-one coaching their employers can gain immensely, too.
Variables such as age, birth order, gender, and family size are tremendous considerations, and parents hoping to enhance the sibling bond gain immensely from understanding these predictors.
British politics can gain immensely from someone of this background, whose name opens doors, and whose connections to a secular culture within the Islamic world could build bridges where few possibilities sometimes seem to exist.
Trump, who said he would be a "big loser" if the bill passed, stands to gain immensely from the Republican tax overhaul, including through a lower top tax rate and lucrative deductions for top-earning households, according to attorneys and tax experts who reviewed the final bill.
Her partner, Semyon Chudin, has gained immensely in assurance since New York's last Bolshoi season three years ago.
Mr. Ramasar, a workshop favorite last spring, has gained immensely in control and polish without losing any of his endearing eagerness.
The rest of the quartet preferred to let Mr. Carter's abstract drama emerge on its own, but the work, which Mr. Carter has compared to a Pirandello play, gained immensely from Mr. Scheindlin's flair.
But it gained immensely from them, stanching the flow of heroin from Afghanistan and cutting the infiltration routes of Islamic militants who have been part of the Chechen rebellion.
I also studied with Oscar-winner Maximilian Schell in a master's class at USC for a brief time, and gained immensely thereby.
