The Greek word πνεῦμα (pneuma) means in general spirit, but it does not necessarily always refer to the Holy Spirit. In the case of Luke 23:46 it refers to the human spirit and not the Holy Spirit.
Each of us is composed of a body, a soul, and a spirit, as attested to by Paul:
1 Thessalonians 5:23 (RSV)
May the God of peace himself sanctify you wholly; and may your spirit [πνεῦμα] and soul and body be kept sound and blameless at the coming of
Lord Jesus Christ.
Spirit as a component of man is also referred to in Hebrews:
Hebrews 4:12 (RSV)
For the word of God is living and active, sharper than any two-edged sword, piercing to the division of soul and spirit [πνεῦμα], of
marrow, and discerning the thoughts and intentions of the heart.
Russian monk and theologian Theophan the Recluse (1815-1894) elaborated on the nature of the human spirit:
Just what is the spirit? It is that force which God breathed into man
when He created him [Genesis 2:7] ... The human soul, although it
resembles the animal soul in its lowest part, is incomparably superior
to it in its highest part. That it is this way in man is because of
its bonding with the soul. The spirit, breathed by God, combined with
it and raised it far above every non human soul.
The spirit as a force proceeding from God, knows God, seeks after God
and only in Him finds its rest. By means of some kind of hidden
spiritual sensitivity, the spirit is convinced of its origin in God.
The spirit feels its total dependency on Him and acknowledges that it
is obliged to please God in every way and live in Him and for Him.
The Spiritual Life and How to Be Attuned to It (St. Paisius Serbian
Orthodox Monastery, 2003), p. 46-47
Orthodox writer Tauschev Averky (1906-1976) wrote on the confusion today between what is "soul" and what is "spirit":
A person’s spirit is completely ignored by our contemporaries. They
combine the spirit and the soul into one. Moreover, in contemporary
psychology, the manifestations of the spirit are perceived to be part
of the life of the soul— religious feeling, moral feeling, and the
conscience are considered part of the soul’s functions. Materialists
reject the soul completely and consider its functions as part of the
brain and nervous system. Consequently, they deem spiritual life to be
materialistic manifestations, examining them as brain functions, the
nervous system, etc. Here, we have the crudest and most primitive
profanation of what we understand to be spiritual life. Modern man
frequently does not differentiate between the actions of the body, the
soul, and the spiritual life, thus mixing them up, creating total
confusion. It comes as no surprise now when we hear the expression
“spiritual life,” which can mean absolutely anything except that which
is authentic spiritual life. Science, and all types of discoveries and
inventions— cinema, theater, ballet, and even the circus— are lumped
together into the area of spirituality. In other words, what is
emotional or natural is assumed to be spiritual and that which relates
exclusively to the secular is misunderstood to be “spiritual life.”
The Struggle for Virtue: Asceticism in a Modern Secular Society (Holy Trinity Monastery, 2011), p. 26