I am confused about the usage of "to" before the word "share" in the following sentence:

We aspire to play a leading role in helping people to share and acquire new knowledge through seminars.

Someone suggested to me that "to" before "share" was not required. Is there any rule which governs such a usage?

I would leave it in, myself, I think either form is ok.
'Help' can be followed by either the to-infinitive or the bare infinitive (infinitive without 'to'):

"Will you help me clear the table?"
"This book helped me to see the truth."

In the first example, external help is called in; in the second, assistance is outside the action proper.
The bare infinitive seems to be more common in AmE than in BrE, but in both varieties the choice is conditioned by the subject's involvement.

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That sentence sounds perfect to me. Miriam what do you think?
 miriam's reply was promoted to an answer.
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