Srimad BhagavadGita

In B.G 2.7 Arjuna asks Kṛṣṇa yacchreyaḥ syān niścitaṃ brūhi (Tell me that which is conclusively best for me?) In this śloka Kṛṣṇa responds to this request from Arjuna and tells him what is best for him. Kṛṣṇa says, "If slain in this righteous war you will attain liberation, if victorious you shall enjoy the kingdom on earth. Therefore, O Kuntiputrā ! Arise with the firm resolve to fight."

In a righteous war, whether it is killing enemies or getting killed by the enemy, for a valorous warrior both fetch extraordinary rewards. Kṛṣṇa is therefore instructing Arjuna to arise and fight.  

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hato vā If you get killed by others in a righteous war.

prāpsyasi svargaṃ (You will attain mokṣa) From the statement yanna duḥkhena saṃbhinnam Mahābhārata Udyoga Parva (since there is not the slightest tinge of misery in swarga (heaven)), we come to know that the word swarga primarily refers to the highest reward called mokṣa. Moreover, this chapter of the Bhagawad Gītā deals with the means to attain mokṣa. Also, in śloka 2.8 Arjuna referred to Indra's heaven where the suras (gods) reside and said that he was not interested in that reward. For these reasons it is appropriate to take the meaning of swarga as mokṣa here and not Indra's heaven. In the below statements from vedanta too we see that mokṣa loka is referred to as swarga loka. sa etān prājñenātmanā asmāllokā dutkramya amuṣmin swarge loke sarvān kāmānāppai amrutassamabhavat Aitareya Up 3.4 (That jīva led by Paramapuruṣa gets started from this lokā and attains liberation in swarga (moksa) loka where all his desires get fulfilled) anante swarge loke jyeya pratitiṣṭati Kena Up 4.9 (he resides in the permanent, very special swarga (mokṣa) lokā. swargaloke amrutatvam bhajante Kaṭha Up 1.1.13 (one who attains liberation in swarga attains his inherent nature endowed with eight qualities).

jitvā vā bhokṣyase mahīm If you attain victory in the war by slaying mahārathis like Bhīṣma and Droṇa, you will enjoy unrivalled kingdom on earth. Even though gaining the kingdom holds no value for you, by fighting this war selflessly which is your means to liberation, you will gain the temporary pleasure of ruling over the kingdom in the near future and the permanent reward of mokṣa after that. Therefore, O Arjuna! Do not worry about your fate. Since the same rule applies to Bhīṣma, Droṇa and others too, there is no need for you to feel for them.

tasmāt yuddhāya kṛta-niścayaḥ uttiṣṭha  O Arjuna! Since both the outcomes of war will reward you mokṣa, arise with the firm resolve to fight.

kaunteya (You, who is Kunti's son) Does it suit a lion cub to walk like a fawn (deer's young one)? Does it suit a Kṣatriya's son to fear death? mṛtham sūte kṣatriyā rājaputri Mahābhārata Droṇa Parva 77.18 (A kṣatriya queen delivers a dead child at birth itself) This means that at the time of your birth itself your mother was mentally prepared to lose you at war any moment . You are the son of my aunt who is such an illustrious woman, hence do not give up your primary duty of fighting this righteous war.