I will help you to acquire Russian.
A native English speaker corrected me saying that 'to' is unnecessary here. Is it correct to say
"I will help you acquire Russian"
After the verb Help, you can have an infinitive form of verb. The infinitive form can be either a to-infinitive or a bare infinitive. That is actually optional. Mostly in conversation or informal English, the to is often left out.
He helps him (to) learn Russian.
Alex helped a blind man (to) cross the road.
N.B So a bare infinitive as well as an infinitive with to is both acceptable after help. But it's observed that in BrE the to-infinitive form dominates, though bare infinitive also occurs in BrE. On the other hand in AmE a bare infinitive is preferable. When there is a repetition of to (a pattern of to + help + to + verb) as in this sentence - she allowed Pearl to help her to stack up her hair - a bare infinitive is generally occurs. Another place where bare infinitive is preferred is when there is an intervening noun phrase as in help people break the cycle of poverty. Bryan A. Garner writes the better usage is to use bare infinitive after help, while Pam Peter says the preference of to-infinitive in BrE is because of their conservatism but this practice is changing.
Some pattern with help from Google’s Ngram viewer
For the help + (to) learn
For the help + (to) do
For the help + (to) dig
I've just found out that a native speaker would rather use the bare infinitive than the to+infinitive form. I was even taught that bringing in the infinitive (with "to") in the sentence is grammatically wrong, but Google proved me wrong.
Help+object+bare infinitive (i.e.: basic form of the verb without "to")
I helped the tourists find the restaurant they sought.
Graham helped the old dude walk up the stairs.
Will she be able to help maintain the peace?
The construction was "to help to do", But to help is used so often with an infinitive that speakers began to consider it something like a modal verb such as can, may etc and began dropping "to".
"to help" isn't yet a modal verb but the drop of "to" might be a first step to changing the status of this verb. Have a look at "need". It can be used as a full verb and as a modal verb.
Today it is almost normal to use "to help" with bare infinitive. But it wouldn't be wrong if you used the to-infinitive.