I have spent several hours going through related articles on the official Jehovah’s Witness web site trying to find an article that directly answers your question. I sincerely doubt that there is a “yes” or a “no” answer but I have found some useful quotes that shed light on how the Witnesses view other Christians. First, we need to understand that Jehovah’s Witnesses believe they are the only true Christians and that Jehovah has appointed them as his sole earthly organisation, and only they are Jehovah God's representatives.
With regard to the events surrounding the outpouring of the Holy Spirit at Pentecost, 33 C.E. the Witnesses believe that only 144,000 persons since the time of Jesus can be anointed with Jehovah’s spirit and become part of “spiritual Israel”:
“Bearing Thorough Witness” About God’s Kingdom, Chapter 3, Filled with holy spirit: This stirring account [Pentecost 33 C.E.] describes a milestone in true worship—the founding of the nation of spiritual Israel, the anointed Christian congregation. (Gal. 6:16) But there is more. When Peter addressed the crowd that day, he used the first of three “keys of the kingdom,” each of which would open up special privileges to a different group of people. (Matt. 16:18, 19) This first key made it possible for Jews and Jewish proselytes to accept the good news and to be anointed with God’s holy spirit. They would thus become part of spiritual Israel, and as such, they would have the hope of ruling as kings and priests in the Messianic Kingdom.
Please note that they also believe Witnesses who are not anointed (they have an earthly hope, not a heavenly hope) can also have “a portion” of Jehovah’s spirit, but they are excluded from the new covenant. They apply the expression “the anointed Christian congregation” to themselves.
This is what they have to say about all other Christian denominations:
The sects and churches of Christendom have proved to be destructive of pure Christianity, “the way of the truth.” They are also “sects of destruction” in that their false teachers are “bringing speedy destruction upon themselves” and upon those who “follow their acts of loose conduct.” Peter adds: “But as for them [the false teachers], the judgment from of old is not moving slowly, and the destruction of them is not slumbering.” (2 Peter 2:1-3) Such “speedy destruction” will come upon them at the fast-approaching “great tribulation.”
This is how Jehovah’s Witnesses identify the Antichrist:
They promote false ideas related to Jesus. (Matthew 24:9, 11) For example, those who teach the Trinity or that Jesus is Almighty God actually oppose the teachings of Jesus, who said: “The Father is greater than I am.”—John 14:28.
Antichrists reject what Jesus said about how God’s Kingdom operates. For instance, some religious leaders say that Christ works through human governments. Yet, this teaching contradicts Jesus, who said: “My Kingdom is no part of this world.”—John 18:36.
They say that Jesus is their Lord, but they do not obey his commands, including the one to preach the good news of the Kingdom.—Matthew 28:19, 20; Luke 6:46; Acts 10:42.
A more up to date publication says this about the people and organisations that are part of the antichrist:
What about today? People and organizations making up the antichrist still oppose Christ and his teachings. They deliberately spread lies and deceptions with the intent of confusing the identity of the Father, Jehovah God, and of His Son, Jesus Christ. We have good reason to beware of such religious deceptions. Let us look at two examples.
For centuries, the churches propagated the doctrine of the Trinity, claiming that the Father and the Son are part of the same entity. The antichrist thus shrouds in mystery the identity of Jehovah God and Jesus Christ. This mystery hinders sincere people from imitating Jesus Christ and drawing close to God, as the Bible encourages them to.—1 Corinthians 11:1; James 4:8.
The churches add to the confusion by promoting the use of Bible translations that omit God’s personal name, Jehovah, from the text. They do this despite the fact that the name Jehovah occurs some 7,000 times in the original text of the Bible. The result? The identity of the true God becomes even more shrouded in mystery.
For centuries, the antichrist has kept millions in spiritual darkness. But by studying God’s Word, the Bible, we are able to learn the true identity of the antichrist and be set free from the antichrist’s religious lies and deceptions.—John 17:17.
Conclusion: The relevance of the above quotes is to show that it is highly unlikely that Jehovah’s Witnesses believe there are other spirit-filled Christians within the realms of Christendom. If I am wrong, then I hope a Jehovah’s Witness will correct me and provide the official view.