The answer to this question is both yes and no. Austen generally, in all of her novels and not just in Emma, uses the omniscient narrator to guide us through the trials and tribulations of her characters. Any cursory examination of this novel reveals the author's voice speaking in to the situation and commenting on her heroine and giving us information about what she is like. Consider the following quote, for example:

The real evils, indeed, of Emma’s situation were the power of having rather too much her own way, and a disposition to think a little too well of herself: these were the disadvantages which threatened alloy to her many enjoyments. The danger, however, was at present so unperceived, that they did not by any means rank as misfortunes with her.

This is a classic case of Austen's authorial voice telling the reader important information about Emma and her character, setting her up for the many hilarious mistakes and errors she subsequently makes as she tries to marry people off to one another.

However, at the same time, Austen in this novel does seem to focus and zoom in on the point of view of Emma at various stages, showing the reader precisely what she experiences and feels and how she changes as a result. Consider this quote, expressing Emma's guilt after she realises that Mr. Elton does not love Harriet but loves her instead:

The first error, and the worst, lay at her door. It was foolish, it was wrong, to take so active a part in bringing any two people together. It was adventuring too far, assuming too much, making light of what ought to be serious—a trick of what ought to be simple. She was quite concerned and ashamed, and resolved to do such things no more.

Austen therefore uses the freedom of the omniscient narrator to focus explicitly on the thoughts and feelings of her heroine and how she feels as a result of the somewhat hilarious mistake she has made. Therefore, it is possible to argue in part that Austen does take the point of view of her heroines, but this is not the case in the novel as a whole.

Does Jane Austen take her heroines' viewpoint in Emma?

Jane Austen does not take the viewpoint of her heroine in the novel Emma. The novel is a comic study of point of view. The heroine, Emma, gets everything wrong. Austen tricks the reader into identifying with Emma and believing what she believes in the case of Frank Churchill--or, in an opposite case, the comedy plays on the audience seeing how disastrously wrong Emma is in steering Harriet away from Robert Martin, the honest farmer, and toward the pretentious Mr. Elton. The novel plays on the slippage between what Emma believes--her own comic misreading of events--and what Austen, the author, knows to be true. It's been called the first mystery novel, in that Austen leaves ample clues for the reader (and Emma) as to what's really going on, but we and she miss them--the joke is on us. As Virginia Woolf says, Austen wrote with laughter in her voice. 

It's important too to remember that a frame for the novel is A Midsummer's Night Dream, Shakespeare's comic study of mishaps and misunderstandings in love. We know this play is a frame, because Emma quotes (or misquotes) a line from the play: "the course of true love never did run smooth" and because an important plot point takes place on Midsummer's day during the strawberry picking party at Donwell (of course, Emma misses the real action). With that frame in mind, it's easier to see the small village of Highbury as the enchanted woods of Shakespeare's play, a place of comic mix-ups, but because of Emma's misreadings of events, not because of faeries and sprites.

Pride and Prejudice is the Austen novel closest to Emma in its study of a lead character, Elizabeth Bennet, who is blinded by prejudice into misreading Mr. Darcy... and Charlotte ... and Wickham. 

Both novels invite readers to question what they believe and why, in novels and in life. Looking particularly at Emma, we see how she is blinded by her own limitations-- for example, she has never been farther than a few miles from her hometown of Highbury--in addition, she has been flattered, fawned on, treated as if she is special, and encouraged to over-value her own judgment, and she has a vested interest in reading events in ways that align with her own ego gratification and desires. As her desires blind us, Austen suggests that all our viewpoints are skewed and unreliable, and cautions that have to be careful what we believe.